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2 ta A survey of subsurface warfare in World War II. 

ta Summary technical report of the National Defense Research 
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1 t a Washington, D.C. : tb Office of Scientific Research and 
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1946. 

ta ix, 340 pages : tb illustrations ; tc 28 cm. 
ta text tb txt t2 rdacontent 
ta unmediated tb n t2 rdamedia 
ta volume tb nc t2 rdacarrier 

ta Summary technical report of Division 6, NDRC ; tv volume 1 
ta Title on half-title page: Summary technical report of the National 
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ta "Manuscript and illustrations for this volume were prepared for 
publication by the Summary Reports Group of the Columbia University 
Division of War Research under contract OEMsr-1 131 with the Office 
of Scientific Research and Development. This volume was printed and 
bound by the Columbia University Press"--Unnumbered page ii. 


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ta In a set of declassified documents held as a collection by the 
Library of Congress. t5 DLC 

ta Includes bibliographical references (pages 321-323) and index. 
0 t a Submarine warfare tx Research tz United States. 

0 ta World War, 1939-1945 tx Naval operations, American. 

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ta pcc 
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0 ta U393 tb ,S7 Div. 6, v. 1 ta V21 0 

2 ta A survey of subsurface warfare in World War II. 

ta Summary technical report of the National Defense Research 
Committee 

1 ta Washington, D.C. : tb Office of Scientific Research and 
Development, National Defense Research Committee, Division 6, tc 
1946. 

ta ix, 340 pages : tb illustrations ; tc 28 cm. 
ta text tb txt t2 rdacontent 
ta unmediated tb n t2 rdamedia 
ta volume tb nc t2 rdacarrier 

ta Summary technical report of Division 6, NDRC ; tv volume 1 
ta Title on half-title page: Summary technical report of the National 
Defense Research Committee. 

ta "Manuscript and illustrations for this volume were prepared for 
publication by the Summary Reports Group of the Columbia University 
Division of War Research under contract OEMsr-1131 with the Office 
of Scientific Research and Development. This volume was printed and 
bound by the Columbia University Press"— Unnumbered page ii. 


500 

500 

504 

650 

650 


ta LC Science, Business & Technology copy no. 305. t5 DLC 
ta In a set of declassified documents held as a collection by the 
Library of Congress. t5 DLC 

ta Includes bibliographical references (pages 321-323) and index. 
0 ta Submarine warfare tx Research tz United States. 

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i . k 

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SUMMARY TECHNICAL REPORT O 


VOLUME 1 


DIVISION 6, NDRC 
DECLASSIFIE D 
By authority Secretary of 


OCT 1 a is 60 

Defense memo 2 August I960 


A SURVEY (^)|P RAEY 0F C0NG RESS 

SUBSURFACE wl\RFARE 
IN WORLD WAR II 


OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT 

VANNEVAR BUSH, DIRECTOR 

NATIONAL DEFENSE RESEARCH COMMITTEE 

JAMES B. CONAN T, CHAIRMAN 

DIVISION 6 
JOHN T. TATE, 



WASHINGTON, D. C., 1946 



NATIONAL DEFENSE RESEARCH COMMITTEE 


James B. Conant, Chairman 
Richard C. Tolman, Vice Chairman 
Roger Adams Army Representative 1 

Frank B. Jewett Navy Representative 2 

Karl T. Compton Commissioner of Patents 3 

Irvin Stewart, Executive Secretary 


1 Army representatives in order of service: 

Maj. Gen. G. V. Strong Col. L. A. Denson 

Maj. Gen. R. C. Moore Col. P. R. Faymonville 

Maj. Gen. C. C. Williams Brig. Gen. E. A. Regnier 

Brig. Gen. W. A. Wood, Jr. Col. M. M. Irvine 

Col. E. A. Routheau 


2 Navy representatives in order of service: 

Rear Adm. H. G. Bowen Rear Adm. J. A. Furer 
Capt. Lybrand P. Smith Rear Adm. A. H. Van Keuren 
Commodore H. A. Schade 
3 Commissioners of Patents in order of service : 
Conway P. Coe Casper W. Ooms 


NOTES ON THE ORGANIZATION OF NDRC 


The duties of the National Defense Research Committee 
were (1) to recommend to the Director of OSRD suitable 
projects and research programs on the instrumentalities 
of warfare, together with contract facilities for carry- 
ing out these projects and programs, and (2) to admin- 
ister the technical and scientific work of the contracts. 
More specifically, NDRC functioned by initiating re- 
search projects on requests from the Army or the Navy, 
or on requests from an allied government transmitted 
through the Liaison Office of OSRD, or on its own con- 
sidered initiative as a result of the experience of its 
members. Proposals prepared by the Division, Panel, or 
Committee for research contracts for performance of the 
work involved in such projects were first reviewed by 
NDRC, and if approved, recommended to the Director of 
OSRD. Upon approval of a proposal by the Director, a 
contract permitting maximum flexibility of scientific 
effort was arranged. The business aspects of the con- 
tract, including such matters as materials, clearances, 
vouchers, patents, priorities, legal matters, and admin- 
istration of patent matters were handled by the Execu- 
tive Secretary of OSRD. 

Originally NDRC administered its work through five 
divisions, each headed by one of the NDRC members. 
These were: 

Division A — Armor and Ordnance 
Division B— Bombs, Fuels, Gases, & Chemical Problems 
Division C — Communication and Transportation 
Division D — Detection, Controls, and Instruments 
Division E — Patents and Inventions 


In a reorganization in the fall of 1942, twenty-three 
administrative divisions, panels, or committees were 
created, each with a chief selected on the basis of his 
outstanding work in the particular field. The NDRC 
members then became a reviewing and advisory group 
to the Director of OSRD. The final organization was as 
follows : 

Division 1 — Ballistic Research 

Division 2— Effects of Impact and Explosion 

Division 3 — Rocket Ordnance 

Division 4 — Ordnance Accessories 

Division 5 — New Missiles 

Division 6— Sub-Surface Warfare 

Division 7 — Fire Control 

Division 8 — Explosives 

Division 9 — Chemistry 

Division 10— Absorbents and Aerosols 

Division 11 — Chemical Engineering 

Division 12 — Transportation 

Division 13 — Electrical Communication 

Division 14 — Radar 

Division 15 — Radio Coordination 

Division 16 — Optics and Camouflage 

Division 17 — Physics 

Division 18 — War Metallurgy 

Division 19 — Miscellaneous 

Applied Mathematics Panel 

Applied Psychology Panel 

Committee on Propagation 

Tropical Deterioration Administrative Committee 


Library of Congress 



2015 


490944 


NDRC FOREWORD 


A S events of the years preceding 1940 re- 
l vealed more and more clearly the serious- 
ness of the world situation, many scientists in 
this country came to realize the need of organ- 
izing scientific research for service in a na- 
tional emergency. Recommendations which 
they made to the White House were given care- 
ful and sympathetic attention, and as a result 
the National Defense Research Committee 
[NDRC] was formed by Executive Order of the 
President in the summer of 1940. The members 
of NDRC, appointed by the President, were in- 
structed to supplement the work of the Army 
and the Navy in the development of the instru- 
mentalities of war. A year later, upon the es- 
tablishment of the Office of Scientific Research 
and Development [OSRD], NDRC became one 
of its units. 

The Summary Technical Report of NDRC is 
a conscientious effort on the part of NDRC to 
summarize and evaluate its work and to present 
it in a useful and permanent form. It com- 
prises some seventy volumes broken into groups 
corresponding to the NDRC Divisions, Panels, 
and Committees. 

The Summary Technical Report of each Di- 
vision, Panel, or Committee is an integral sur- " 
vey of the work of that group. The first volume 
of each group’s report contains a summary of 
the report, stating the problems presented and 
the philosophy of attacking them and summar- 
izing the results of the research, development, 
and training activities undertaken. Some vol- 
umes may be “state of the art” treatises cover- 
ing subjects to which various research groups 
have contributed information. Others may con- 
tain descriptions of devices developed in the 
laboratories. A master index of all these divi- 
sional, panel, and committee reports which to- 
gether constitute the Summary Technical Re- 
port of NDRC is contained in a separate vol- 
ume, which also includes the index of a micro- 
film record of pertinent technical laboratory 
reports and reference material. 

Some of the NDRC-sponsored researches 
which had been declassified by the end of 1945 
were of sufficient popular interest that it was 
found desirable to report them in the form 
of monographs, such as the series on radar by 
Division 14 and the monograph on sampling in- 
spection by the Applied Mathematics Panel. 


Since the material treated in them is not dupli- 
cated in the Summary Technical Report of 
NDRC, the monographs are an important part 
of the story of these aspects of NDRC research. 

In contrast to the information on radar, 
which is of widespread interest and much of 
which is released to the public, the research on 
subsurface warfare is largely classified and is 
of general interest to a more restricted group. 
As a consequence, the report of Division 6 is 
found almost entirely in its Summary Tech- 
nical Report, which runs to over twenty vol- 
umes. The extent of the work of a Division can- 
not therefore be judged solely by the number 
of volumes devoted to it in the Summary Tech- 
nical Report of NDRC : account must be taken 
of the monographs^ and available reports pub- 
lished 

^ny a g£ea$i iqoo^mfiw enteavor must stand 
or fall with the will and integrity of the men 
engaged in>4t. . held true for NDRC 

from itsnncep'tion, and for Division 6 under 
the leadership of Dr. John T. r Tate. To Dr. Tate 
ahd r ^ho w olfed with him — some as 

memlj^^<^D^|siqp^ representatives 

of tKe’Division’s contractors — belongs the sin- 
cere gratitude of the Nation for a difficult and 
often dangerous job well done. Their efforts 
contributed significantly to the outcome of our 
naval operations during the war and richly 
deserved the warm response they received from 
the Navy. In addition, their contributions to 
the knowledge of the ocean and to the art of 
oceanographic research will assuredly speed 
peacetime investigations in this field and bring 
rich benefits to all mankind. 

The Summary Technical Report of Division 
6, prepared under the direction of the Division 
Chief and authorized by him for publication, 
not only presents the methods and results of 
widely varied research and development pro- 
grams but is essentially a record of the un- 
stinted loyal cooperation of able men linked in 
a common effort to contribute to the defense of 
their Nation. To them all we extend our deep 
appreciation. 

Vannevar Bush, Director 
Office of Scientific Research and Development 
J. B. Conant, Chairman 

National Defense Research Committeenr^G 


CRET 


A^cation 
Scumbn'E f ^ r - be CAWLBSi 


DOCTJMEN 
























































































































1 









































































• ' *, 





















PREFACE 


T his first volume of the Summary Techni- 
cal Report of Division 6, NDRC is an over- 
all account of the Division's activities. It is 
written for those whose chief interest lies not 
so much in the technical details of the program 
as in the general philosophy which determined 
the form of organization, the nature of the 
services undertaken, and how these were inte- 
grated with the bureaus and operating forces 
of the Navy. 

The unique feature of Division 6 was that its 
responsibility was not to develop a particular 
instrumentality of war or to exploit a particu- 
lar field of science for military purposes, but 
was to assist the Navy in all ways in which 
men of scientific and engineering experience 
and skill could significantly contribute to the 
prosecution of subsurface warfare. In the re- 
stricted fields of submarine and antisubmarine 
warfare, therefore, the problem facing the 
Navy and Division 6 was the general one: 
through what plan of organization might the 
scientific and technological resources of the 
country be made available to the military serv- 
ices for the prosecution of the war and for the 
maintenance of national security through con- 
tinued technological preparedness? 

As the reader will note, this volume is a com- 
pendium of contributions by a number of au- 
thors, all former members of Division 6 or its 
contractors' laboratories. This method of pres- 
entation was chosen in the full knowledge that 
the volume would lack that uniformity of style 
to be expected were the writing done by a single 
author and that some repetitiousness was 
bound to result from the fact that two or more 
contributors would choose to discuss aspects of 
subsurface warfare common to more than one 
field of specialization. But it was felt that these 
disadvantages were minor as compared with 
the great advantage of having the parts and 
chapters and sections which compose the vol- 
ume each written by the one author best quali- 


fied by first-hand experience to deal with the 
subject under consideration. 

The authors who contributed to the writing 
of this volume are John T. Tate, Chief of Divi- 
sion 6 ; Philip M. Morse, Director of the Opera- 
tions Research Group under first NDRC and 
later the Navy; Elmer Hutchisson, Chief Tech- 
nical Aide of the Division; Edwin H. Colpitts, 
Chief of Section 6.1; Carl Eckart, Associate 
Director of the San Diego Laboratory; Fred- 
erick V. Hunt, Director of the Harvard Under- 
water Sound Laboratory; Franz N. D. Kurie, 
Associate Director of the San Diego Labora- 
tory; Robert S. Shankland, Director of the Un- 
derwater Sound Reference Laboratory; Rob- 
ert T. Knapp, Head of the Fluid Dynamics Re- 
search Group ; William V. Houston, Director of 
the Columbia University Special Studies 
Group; Timothy E. Shea, who, as Director of 
Research for the Columbia University Divi- 
sion of War Research, organized and guided 
the activities of the Field Engineering Group; 
Gaylord P. Harnwell, Director of the San Diego 
Laboratory and Chairman of the Committee on 
Selection and Training; and the editor. The 
Division and the Summary Reports Group are 
extremely grateful to these men for their con- 
tributions to both this and the other volumes 
of the Division 6 Summary Technical Report. 

It is hoped that the reader will keep in mind 
that this volume, as its title indicates, reviews 
the activities in subsurface warfare of Division 
6 only ; and only insofar as they concern or im- 
pinge on the program of Division 6 is any at- 
tempt made to discuss the manifold activities 
of the Navy, our Allies, other Divisions of 
NDRC, and many other agencies, governmental 
and private, which contributed to the develop- 
ment and use of the equipment and tactics 
which won final victory in subsurface warfare. 

John S. Coleman, 

Editor, Division 6 


Vll 






CONTENTS 


CHAPTER p AGE 

Introduction 1 

PART I 

ORGANIZA TION AND ACTIVITIES OF 
DIVISION 6 

1 The Antisubmarine Problem by Philip M. 

Morse 7 

2 Scope of Division Activities by Edwin H. Col- 

pitts 21 

3 Organization of the Subsurface Warfare Group 

by Elmer Hutchisson 26 

PART II 

OPERATIONS RESEARCH 

4 The Role of Operations Research in Antisub- 
marine Warfare by Philip M. Morse ... 75 

5 NDRC Background by Philip M. Morse . . 81 

6 Development of U. S. Operations Research by 

Philip M. Morse 85 

7 Research Activities by Philip M. Morse . . 97 

PART III 

PHYSICAL RESEARCH 

8 Fundamental Studies of Underwater Sound by 

Carl Eckart 119 

9 Transducer Research and Calibration by 

Robert S. Shankland, Frederick V . Hunt , and 
Franz N. D. Kurie 144 

10 Torpedoes and Fluid Dynamics by William V. 

Houston and Robert T. Knapp 161 

PART IV 

EQUIPMENT DEVELOPMENT 

1 1 Antisubmarine Detection Equipment by John 

S. Coleman 177 

12 Prosubmarine Equipment by John S. Coleman 198 

13 Acoustic Torpedoes by Eric Walker . . . 209 

PART V 

TRAINING AND MAINTENANCE 

14 Assistance to the Navy in Technical Training 

by Gaylord P. Harnwell 225 

15 Field Engineering by Timothy E. Shea . . 279 

Appendix A-I 301 

Bibliography 321 

OSRD Appointees 324 

Contract Numbers 325 

Service Project Numbers 330 

Index 335 


























































































INTRODUCTION 

By John T. Tate 


I N two world wars the submarine has dem- 
onstrated its deadly effectiveness. It cannot 
be repeated too often nor with too great empha- 
sis that the margin of Allied victory over the 
U-boat in both wars was narrow and precarious 
and that the U-boat emerged from the recent 
war potentially more dangerous than at the 
beginning. Had the Nazis been a little more 
imaginative, had their leaders better exploited 
the scientific and technical skills at their com- 
mand so as to anticipate by six months or a 
year the service use of new submarine types 
which were under development or just com- 
pleted when the war was already lost, the out- 
come might well have been different. For these 
new type submarines would have rendered ob- 
solete much of the Allied antisubmarine equip- 
ment and tactics. Lest we be lulled into a false 
sense of security the stark fact should be em- 
phasized that today we are technologically un- 
prepared to cope with the U-boats which the 
Nazis had on the point of readiness for opera- 
tional use in 1945 when the war was already 
lost by them. 

Fortunately the Allies did win the upper 
hand in the battle of the Atlantic and were able 
to hold it long enough to win the war with Ger- 
many, but only after a staggering loss of mil- 
lions of tons of shipping and of vital materiel 
and with the knowledge that had the war con- 
tinued for another year they might again have 
lost control. 

On the other hand, the Japanese lost the 
battle with our own submarines in the Pacific, 
and the consequences of that loss are an object 
lesson to those who may doubt the necessity for 
continuing into peacetime the research and de- 
velopment necessary to keep abreast in the 
contest of wits which is subsurface warfare. 

The balance of power in submarine and anti- 
submarine warfare is peculiarly sensitive to 
scientific and technological developments rather 
than to the brute force of numbers. In two 
world wars the U-boat almost singlehanded 
narrowly missed victory over the two most 
powerful navies in the world. 


Another consideration of particular concern 
to a militarily nonaggressive country such as 
ours is that continental isolation is meaningless 
to the submarine. An aggressive enemy could 
strike against our vital shipping lanes at once 
and with full strength, and press the attack up 
to our home ports. Distance would give us no 
time for preparation. 

It is sometimes argued that developments 
such as radar, guided missiles, and the atomic 
bomb, will so change the pattern of naval war- 
fare that the submarine will be obsolete. On 
the contrary there is every reason to believe 
that in a future war the submarine will be 
called upon to play a much more vital part than 
in the past. The operational reports of the last 
few months of World War II indicate a widen- 
ing differential between the safety of the sub- 
marine and that of surface craft. The naval 
losses at Okinawa due to suicide planes indi- 
cate the future danger to concentrations of sur- 
face forces from various types of guided mis- 
siles— a danger made more intense by the possi- 
bilities of the atomic bomb. On the other hand 
the great difficulty encountered in detecting 
and attacking U-boats equipped with Schnor- 
chel emphasizes again the great difficulty in 
locating and destroying a submerged vessel. It 
is likely therefore that in the event of World 
War III greater reliance and greater responsi- 
bility will be placed on submersibles than in the 
past. In a technological sense the submarine as 
an instrument of war is in its infancy. 

Although later on we shall indicate certain 
lines of investigation and development which 
at present appear fruitful it is with no thought 
that such suggestions have more than transient 
value. As already noted, there is every likeli- 
hood that the pattern of subsurface warfare 
will be radically changed in the event of a fu- 
ture conflict. This may come about because of 
the particular nature of the resources and geo- 
graphical location of the opposing nations. It 
will almost certainly come about because of 
scientific and technical advances — most of 
which will have originated with no specific ref- 


1 


2 


INTRODUCTION 


erence to subsurface warfare. If there is any- 
thing of permanent value in the present dis- 
cussion it is that which relates to the manner in 
which we may at all times be aware of our state 
of preparedness or lack of it and be assured 
that our research and development program is 
relevant to the needs of the situation. 

Apart from the explosiveness of the action 
and the violence and deadliness of the competi- 
tion, warfare resembles a huge, technical, com- 
petitive service enterprise involving millions 
of men and their coordinated use of an immense 
and complex variety of technical equipment. 
There are three principal activities of this 
enterprise — each distinct in function but each 
vital to success. They are operations, produc- 
tion, and research. The inherent differences in 
function, in viewpoint, in skills, and in mode of 
procedure inevitably requires that these three 
divisions of the enterprise be distinct with re- 
spect to organization and lines of authority and 
responsibility. 

Each is a specialized field which demands of 
its leaders long experience and breadth of 
knowledge and understanding in these special- 
ties. The director of research, for example, 
should have the qualities demanded of the di- 
rector of research of a great industrial research 
laboratory and a place in the overall enterprise 
of equal prestige and responsibility. 

The distinctness of organization of these 
three divisions — so necessary for their indi- 
vidual functioning — does not imply any lack of 
necessity for complete cross correlation and 
liaison all down the line in each. There is but a 
single measure of success of the entire enter- 
prise and that is success in the operating divi- 
sion. For this reason the top policy and pro- 
gramming level of each division must join to- 
gether for planning and for mutual understand- 
ing. 

In reaching conclusions, this combined plan- 
ning body must have before them the results of 
a continuing, thoroughgoing analysis of opera- 
tions (actual operations in time of war, simu- 
lated operations in time of peace) — an analysis 
of the performance of men and equipment not 
only as individuals but as elements in the over- 
all system. Such a system demands teamwork 
among men and coordinated functioning of 


equipment to accomplish the final objective. 

No type of warfare lends itself better to illus- 
trate the force of the above conclusions than 
subsurface warfare; antisubmarine warfare, 
for example, and in particular, the attack on a 
submerged submarine by a surface vessel. Al- 
though, as already noted, the Naval Research 
Laboratory had developed an efficient detection 
and location device, we entered this war with 
the same crude ordnance, the depth charge, 
which was used in World War I. What was 
more serious we had an unrealistic notion of 
the effectiveness of this combination of equip- 
ment. No really scientific analysis of the opera- 
tion had been made or the glaring ineffective- 
ness of the “ash can” depth charge would have 
been so obvious that research to develop more 
effective ordnance would have been undertaken 
long since. Not until our Navy so wisely cen- 
tralized control of A/S warfare operations in 
the Tenth Fleet, attached to it the Operations 
Research Group, and established ASDevLant to 
simulate operations, to study and develop tac- 
tics in the use of equipment, and brought the 
leaders of research groups into their full con- 
fidence was there assurance that research pro- 
grams were kept relevant to operational needs 
and that first things were being put first. 

These matters of organization and function 
are stressed because they are vital to future 
preparedness. There can be no substitute for 
exact knowledge of the state of our prepared- 
ness as the first step in any program to assure 
the future security of the nation. This knowl- 
edge cannot be gained through casual observa- 
tion and opinion but only by the cold-blooded 
objective methods of science. 

As to the foreseeable needs for research and 
development in subsurface warfare, only 
major aspects can here be discussed. 

As already noted, the development of radar, 
guided missiles, and the atomic bomb are likely 
to call upon the submarine to play an even more 
important role as an offensive weapon in the 
event of a future war. One of the most impor- 
tant development tasks facing the Navy is the 
perfecting of a high-speed (both on the surface 
and submerged) submarine capable of long en- 
durance at high speed under water. It must be 
made to be as silent as possible at high under- 


INTRODUCTION 


3 


water speed and as “dead” as possible to radar 
or sonar reflection. Because of the desirability 
of silent operation and for other safety reasons 
it should be capable of submergence to a depth 
of 1,000 ft or more. Submersibles capable of 
carrying guided missiles and launching facili- 
ties should be developed. 

These foreseeable possibilities for the devel- 
opment of the submarine make necessary the 
perfection of antisubmarine measures to 
counter them. Antisubmarine ships must be de- 
veloped capable of a speed superior to that of 
the submarine and equipped with detection and 
locating gear which will operate reliably at 
these speeds. This gear should be continuously 
and automatically alert in all directions and be 
capable of revealing not only the range but the 
depth of the submarine. Ordnance must be de- 
vised for the certain destruction of the sub- 
marine when detected. This will probably take 
the form of homing torpedoes which are self- 
guided to the submarine by the same means as 
that used by the surface ship for detecting it. 
There is every reason to believe that the sub- 
marine can be developed to the point where in 
battle with surface craft the submarine will 
have every advantage. For this reason great 
emphasis should be placed on the full develop- 
ment of aircraft for antisubmarine use. This 
will involve the perfection of means for detect- 
ing and locating submerged submarines from 
aircraft, and ordnance which when dropped 
from aircraft will seek out and overtake the 
submarine. 

These foreseeable countermeasures to the 
submarine suggest counter-countermeasures 
for submarine equipment among which are 
early warning equipment to detect radar or 
sonar search, homing torpedoes to destroy an 
attacking surface craft, coating of hull to re- 
duce reflecting power for radar and sonar, de- 
vices for jamming radar and sonar; devices for 
decoying homing torpedoes away from the 
submarine, and devices for detecting torpedoes. 

The engineering research and development 
necessary to accomplish these ends are suffi- 
ciently obvious to require little comment. They 
involve among many other matters the follow- 
ing: studies of hull design for submersibles to 
achieve strength for deep submergence, resist- 


ance to shock, streamlining for high under- 
water speed and silence ; an intensive study of 
means for reducing machinery noises; studies 
of methods of propulsion and of fuels to make 
possible long submergence (6 hours or more) 
at high speeds (25 knots or more) . It is not too 
early to give great attention to the development 
of atomic energy as a power source for sub- 
mersibles. 

In addition to engineering research there are 
certain fields of basic research of particular 
importance to subsurface warfare which should 
be continued energetically. 

1. Oceanography. The medium in which the 
submarine moves is the ocean. Both the design 
and tactical use of submarines require as com- 
plete knowledge as possible of the physical 
character of this medium — the temperature, 
salinity, and density gradients; the currents; 
the bottom characteristics — all as they depend 
on locality and time of year. 

2. Underwater acoustics. At present the only 
form of energy known tor science which can be 
used for detection of submerged objects at 
ranges greater than a few hundred feet is 
sound energy. For this reason the basic study 
of all aspects of sound transmission, reflection, 
refraction, reverberation, scattering, should be 
intensively continued. 

3. Hydrodynamics. It is obvious that the 

study of the motion of objects through water 

the stability, the resistance to motion, cavita- 
tion, manner of propulsion— is vital to the de- 
sign of submarine hulls and types of ordnance. 
In the case of torpedoes dropped from aircraft 
the problems of water entry need further basic 
study. 

Let it be emphasized again that perfection 
in the operation of entire systems of men and 
equipment is the sole criterion of success in a 
research and development program for subsur- 
face warfare; that the performance of these 
systems must be continually subject to critical 
analysis ; and that the research leaders must 
study this analysis. On the other hand those in 
charge of the research program must be in 
touch with, and professionally a part of, the 
general scientific life of the country. In no 
other way will they be able intelligently to di- 
rect and to keep relevant a program of research 


4 


INTRODUCTION 


which will assure the continued readiness of 
our Navy in subsurface warfare. 

Few aspects, therefore, of continuing pre- 
paredness for national defense deserve more 
careful consideration than those concerned 
with submarine and antisubmarine warfare. It 
is to aid in such consideration that Division 6, 
the subsurface warfare division of NDRC, has 
prepared the present series of technical re- 
ports. During World War II, Division 6 joined 
with the Navy and with other agencies in an 
intensive effort to mobilize the scientific and 
technical talent of the country to assist in the 
defeat of the U-boat and in strengthening the 
striking power and safety of our own sub- 
marines. The division sponsored a broad pro- 
gram of research in those aspects of physical 
oceanography, of underwater acoustics, and of 
fluid dynamics which must form the basis of the 
proper design of submarine and antisubmarine 
equipment and ordnance. The results of this 
program have permanent value. 

The division organized and trained groups of 
scientists and engineers to join with the Navy 
in the performance of special services essential 
to the effective use of men and equipment in 
the conduct of subsurface warfare. The form 
of organization, the methods and techniques 


developed for these services — for operational 
analysis, for field engineering, for the selection 
and training of personnel — have permanent 
value. 

The division developed many new and im- 
proved devices for offense and defense in sub- 
surface warfare. Although most of these, even 
those which proved so effective in World War 
II are, or soon will become obsolete, many are 
capable of further development and refinement 
to meet new requirements. In any case the les- 
sons learned in this development program are 
of future value. 

It is to preserve the permanent values of this 
extensive wartime program of Division 6, to 
present them in coherent form for the use of 
those agencies which may continue to be con- 
cerned with readiness for defense in this type 
of warfare that this series of summary techni- 
cal reports has been prepared. At the same 
time, of course, these reports form a record of 
accomplishment in a joint Navy-NDRC enter- 
prise in which both agencies may take pride. 
For in a very real sense it was a joint enter- 
prise and the manner and extent of the coordi- 
nation of the division's organization and activi- 
ties with those of the Navy deserve special em- 
phasis. 


PART I 


ORGANIZATION AND ACTIVITIES OF DIVISION 6 




Chapter 1 

THE ANTISUBMARINE PROBLEM 

By Philip M. Morse 


T he submarine was still impractical in 
1890 when Mahan’s The Influence of Sea 
Poiver upon History was published. True, 
Bushnell had traveled some thousands of feet 
under water during the American Revolution, 
but his endeavors were abortive ; Fulton poured 
a great deal of his inventive genius and enthusi- 
asm into the design of a submersible, but the re- 
sults were disappointing. The necessary power 
plants had yet to be perfected. Not until a few 
years after 1900 could the internal combustion 
engine for surface running be used with the 
electric battery motor for submerged running 
to create a practicable combination. During the 
first decade of the twentieth century the Amer- 
ican inventors, Holland, Lake, and others, rap- 
idly developed the submarine into a practicable 
naval vessel — ready for effective use by the 
Germans in World War I. 

Though the introduction of the submarine 
changed the tactical picture, it did not change 
the rules of grand strategy outlined by Mahan. 
As was so well stated by Brodie in 1944 in A 
Guide to Naval Strategy: 

Sea power has never meant merely war ships. It has 
always meant the sum total of those weapons, installa- 
tions, and geographical circumstances which enable a 
nation to control transportation over the seas during 
wartime. If the airplane (or submarine) plays an im- 
portant part in such a control, it is functioning as an 
instrument of sea power. All naval enterprise — with 
the exception of bombardment of land objectives from 
the sea, which is only an incidental use of sea power 
— is directed toward the single aim of affecting the 
movement of the lowly freighter or transport in which 
are carried nearly all the commodities and the men 
that move across the sea. 

Control of the sea has usually gone to that 
side which had the greatest number of war- 
ships. The weaker naval powers have always 
tried to break down this control by the use of 
vessels which could sink the enemy’s merchant 
shipping in spite of his predominating battle 
fleet, the so-called guerre de course. In Napole- 
onic wars the privateer was tried against the 
English naval power and failed. As used by the 


Allies’ enemies in both World Wars, the sub- 
marine played the role of a modern privateer, 
which was expected to sink Allied merchant 
shipping despite the Allies’ greater naval 
power. 

The submarines of the enemy almost suc- 
ceeded in both World Wars — but they did not 
succeed. This story of the activities and 
achievements of NDRC’s subsurface warfare 
group includes a partial list of the technical 
reasons why submarines have not yet broken 
Allied sea power, and will indicate, it is hoped, 
the narrowness of the present margin of safety. 

11 THE LOGISTICAL PROBLEM 

For the past 40 years Great Britain has 
maintained afloat approximately 20,000,000 
gross tons a of merchant shipping: about 2,500 
ocean-going vessels of 6,500 gross tons average, 
and about 2,500 coastal ships of 1,200 gross 
tons average. Her allies in the two wars have 
had about another 20,000,000 gross tons avail- 
able. A sizable part of this fleet is needed to 
keep England fed and supplied in a war when 
no supplies can be obtained from Europe. 

In 1943 the total imports to the United King- 
dom averaged about 3,600,000 long tons a 
month, more than 80 per cent of this being car- 
ried by the North Atlantic convoy system. To 
make a round trip, the average ship in the 
North Atlantic convoy system took about 70 
days, half of which were spent at sea and the 
other half in port. Therefore, a flow of 10 ships 
a month, of 6,500 gross tons apiece, would re- 
quire a fleet of about 24 ships in commission. A 
ship of this size carries about 8,000 long tons 
per trip. From these figures, we see that in 
1943 the United Kingdom needed a fleet of be- 
tween 7,000,000 and 10,000,000 gross tons just 
to keep fed and supplied. 

a A gross ton is a measure of total internal cubic 
capacity of the ship, expressed in tons of 100 cu ft to 
the ton. A ship of 1,000 gross tons capacity will, as a 
rule, be able to carry more than 1,000 long tons of 
freight. 


7 


8 


THE ANTISUBMARINE PROBLEM 


But the United States and other Allied na- 
tions in World War II sent great expeditionary 
forces overseas, eventually into continental 
Europe. These immense armies had to be sup- 
plied by sea. The average soldier was accom- 
panied by about 5 tons of equipment and sup- 
plies when he went, and after his arrival he 
needed an additional ton per month. Since com- 
plete replacements were needed once a year on 
the average, each soldier maintained in Europe 
needed between 16 and 20 long tons shipped 
across each year to keep him fighting. Again 
utilizing the previous figures, we see that each 
soldier needed on the average between 3 and 5 
gross tons of shipping to keep him steadily sup- 
plied, or an army of 5 million men in Europe 
required a fleet of 20 million gross tons total 
continually plying the Atlantic to keep it going. 

These figures simply serve to illustrate the 
obvious fact that the sinking of merchant ves- 
sels reduces our ability to fight overseas and 
that the Allied margin of safety in this respect 
is extremely small. In World War I and World 
War II the U-boats of Germany plus the sub- 
marines of Italy and Japan reduced Allied 
shipping strength to a level close to the danger 
mark. In addition it disrupted the naval build- 
ing program and in World War II it delayed the 
building of vitally needed landing craft. There 
is no reason to believe that the threat will be 
any less should there be a next time. 

In World War II, of course, the United States 
also sent a great force to the Pacific theater. 
The Japanese never used their submarines a 
fraction so effectively as the Germans, but the 
problem of supply over ocean routes far longer 
than those of the Atlantic was one that re- 
quired more millions of tons of shipping. 

12 CONVOYS 

It is not 30 times easier to find 30 ships to- 
gether than to find one ship. Consequently it is 
harder for a privateer to find a convoy of 30 
ships than it is to find some ships if the 30 are 
spread over the ocean in independent routings. 
This advantage of concentration, however, 
would be more than counterbalanced if the pri- 
vateer, once the convoy is found, could maintain 
the attack long enough to sink the same per- 
centage of ships no matter how large the con- 


voy. In Napoleonic times the exigencies of sail- 
ing-vessel tactics made it difficult to continue 
the attack for long, so that usually a smaller 
percentage of ships were destroyed out of a 
large convoy than out of a small convoy. Conse- 
quently, convoying was a useful defense against 
privateers in Napoleonic times, even when no 
naval escort vessels accompanied the convoy. 

In the latter part of the nineteenth century, 
with the development of the dreadnought-type 
warship, it was believed that the advantages of 
convoying had disappeared. This belief carried 
over into the planning of antisubmarine war- 
fare in World War I and nearly lost the battle 
for England. Finally the suggestions of Ad- 
mirals Sims and Jellicoe and others prevailed, 
and convoying was tried, even though the num- 
ber of escort vessels was considered to be inade- 
quate. The introduction of convoying in 1917 
immediately cut the monthly toll of sinkings to 
approximately half its previous value. As the 
number of escort vessels accompanying the 
convoys was increased, the sinkings dropped 
still further. 

Thus, the introduction of convoying defeated 
the submarine in World War I and maintained 
Allied control of the sea, although precariously. 
The North Sea mine barrage solidified this con- 
trol though the barrage was completed so late 
in the war that it was not possible to determine 
exactly how efficacious it was. In World War II 
convoying again proved its value. The mine 
barrage could not be used, but a new element 
effective against the submarine entered into 
the picture — the airplane. 

13 EXPERIENCE OF WORLD WAR I 

The German blueprint for World War I did 
not contemplate use of the submarine as a 
means of denying the British freedom of the 
seas. The German plan, as was to be true also 
in the case of World War II, was for a short 
war where overseas supply could be ignored. 
Surface raiders were tried sporadically during 
the first year. The results were not promising. 
But the Germans’ few submarines immediately 
showed profitable returns. Crude as the World 
War I U-boats were, compared to their World 
War II successors, and undeveloped as were 
their tactics, the first two years’ figures indi- 


THE TECHNICAL PROBLEM 


9 


cated to the Germans that in this modern, sub- 
mersible version of the privateer they had a 
potent weapon. During those years, on the av- 
erage, each U-boat sank about 13,000 gross tons 
of shipping a month. The mean life of the U- 
boat at that time was about 10 months, so that 
each U-boat sank approximately 1 per cent of 
England’s total shipping before it itself was 
sunk. The Germans became convinced that if 
they could build up their submarine fleet to 100 
or 200 U-boats, they might inflict decisive dam- 
age on British shipping. The results showed 
that the German strategists were correct. If 
the English antisubmarine defenses had not 
been improved after 1916, the submarines 
would have blockaded the British Isles. 

In the latter part of 1916, the Germans 
started a large U-boat construction and train- 
ing program. In February 1917 they began a 
large scale campaign of unrestricted submarine 
warfare on merchant shipping, which almost 
proved successful. Allied shipping losses rose 
steadily to a peak of about 900,000 gross tons 
sunk by U-boats in April 1917 ; nearly one- 
twentieth of Britain’s shipping was sunk in 
a month. The British Fleet was confined to its 
bases, for at one time there was only 8 weeks’ 
supply of fuel oil in England. 

In the face of such a crisis, the British at 
last decided to try reviving the ancient expedi- 
ent of convoying. On the part of many in the 
Admiralty, the decision was a reluctant one. 
They expected to gain little advantage. At that 
time only a few destroyers and other antisub- 
marine craft were available for protecting ship- 
ping in the vicinity of England. These craft 
were distributed evenly along the shipping 
lanes on protective patrol, and the merchant 
shipping was routed independently as in peace- 
time. If all transatlantic shipping was to be 
put into convoy, it was felt that each convoy 
should be heavily protected, and there simply 
were not enough escort vessels available. It 
was, however, a desperate case of do the best 
one could and a few convoys were experimen- 
tally allotted such escorts as could be gotten 
together. The results showed promise. Conse- 
quently, in April 1917, convoying was generally 
introduced, and escort vessels were added as 
fast as they were built. By October 1917, 1,500 


ships in 99 convoys had been brought into port 
with a loss of only ten ships sunk while in con- 
voy, a rate of loss considerably smaller than 
that for independent shipping. 

The results of convoying in World War I, and 
also in World War II, have shown that on the 
average the number of ships sunk in a convoy 
which is attacked by submarines is no greater 
for a large convoy than for a small one. Large 
convoys, therefore, have a smaller percentage 
of ships sunk per attack. The percentage di- 
minishes slightly as the number of escort ves- 
sels is increased: for instance, a convoy with 
ten escort vessels is about twice as safe as a 
convoy with three escort vessels. Careful analy- 
sis of the results of both wars indicates that in 
the case of escorted convoys the average num- 
ber of vessels sunk per attack is independent 
of the size of the convoy, is proportional to the 
number of U-boats participating in the attack, 
and is inversely proportional to the square root 
of the number of escort vessels. The size of the 
proportionality factor depends on tactical de- 
tails, and is different for different periods. 

The introduction of convoying eased the situ- 
ation for the Allies but did not solve the anti- 
submarine problem. After the start of unre- 
stricted U-boat warfare early in 1917, the 
Germans maintained an average of about 40 
U-boats at sea at any one time. During this pe- 
riod the average number of U-boats sunk each 
month was only about 7, the maximum number 
of U-boats sunk in any month being 14 in May 
1918. Therefore, the average life of a U-boat 
at sea during the last year of World War I was 
still about 6 months. In the last 4 months of 
World War I each U-boat was still sinking 
about 45,000 gross tons before it itself was 
sunk. The submarine weapon had been dulled 
somewhat, but it remained an extremely dan- 
gerous threat to the Allied control of the seas. 

14 THE TECHNICAL PROBLEM 

Obviously the problem was technical and ex- 
tremely difficult, involving elements quite dif- 
ferent from other naval technical problems. 
The most difficult part was that of detecting 
the position of the submarine at a great enough 
distance so that the threatened vessel might 


10 


THE ANTISUBMARINE PROBLEM 


do something about it, either run away or at- 
tack before the submarine launched its torpedo. 

Salt water is a good medium for concealment. 
It is opaque enough to visual light so that only 
rarely can a submerged submarine be seen. 
Submarines sometimes leak small quantities of 
oil which come to the surface and form a ‘‘slick” 
which can be seen for some distance. It was soon 
found, however, that an oil slick was a very 
unreliable means of detection, for it could be 
confused with similar slicks left by surface 
vessels, and there was no sure way of deter- 
mining how far ahead of the leading edge of 
the slick the submarine was located. The mag- 
netic field of the submarine could be used as a 
means of detecting its presence, but this field 
was imperceptible beyond a few hundred feet. 
Salt water is practically impenetrable by elec- 
tromagnetic waves over wide ranges of wave- 
lengths from a few centimeters to a number 
of meters. The only practicable means of de- 
tecting the submerged submarine seemed to be 
through the use of underwater sound. 

Sound waves in water travel considerable 
distances, although they are diffracted by tem- 
perature and salinity gradients, and are scat- 
tered and reflected from the ocean bottom. Ex- 
cept under unusual conditions, a submarine has 
to be under way to maintain its equilibrium 
while submerged. While it is moving, even very 
slowly, it produces low-frequency noise from 
the machinery and movements inside the hull. 
At higher speeds, it produces high-frequency 
noise from cavitation about the propellers. The 
low-frequency sounds are the louder, but the 
direction of motion of the waves is difficult to 
determine accurately and background noise in 
the low-frequency range may mask the wanted 
sounds entirely. The supersonic waves are more 
directional and less susceptible to masking, but 
they disappear if the submarine slows down. 

Toward the end of World War I, submarine 
chasers were equipped with hydrophones capa- 
ble of hearing the low-frequency sound put out 
by submarines and capable of determining the 
approximate direction of the source by means 
of the binaural effect. The equipment was diffi- 
cult to use successfully. The range of the sound 
source could not be determined ; and the detect- 
ing vessel had to come nearly to rest in order 


that its own noise might not drown out that of 
the submarine. The majority of the submarines 
which were detected in World War I were 
spotted on the surface or their periscopes were 
seen. 

The difficulties of detecting a submerged sub- 
marine are reflected in the data on U-boat 
losses in World War I. In this first struggle, 
178 U-boats were sunk, about 30 per cent being 
sunk by mines before they were able to get out 
of the North Sea. Ten per cent of the U-boat 
losses were due to Allied submarines which 
spotted them on the surface and sank them by 
torpedoes. About 25 per cent were sunk by sur- 
face vessels which caught them on the surface 
and sank them by gunfire or by ramming. Only 
about 20 per cent of the U-boats lost were 
caught and sunk while they were submerged. 
(The other 15 per cent of the losses was not 
due to Allied action.) The detection problem 
was far from being solved, nor is it solved yet. 

In September 1918 a committee was formed 
in England called the Allied Submarine Devices 
Investigation Committee to study the problem 
of improving the range of detection of sub- 
merged U-boats. A method of echo ranging 
using supersonic pulses was proposed which 
would give not only bearing but range. This 
type of gear (called ASDIC, after the initials 
of the proposing committee) was still in the 
experimental stage when World War I ended. 
Work was continued between wars, however, 
and by 1930 both England and the United 
States had practicable supersonic echo-ranging 
detection gear which could be installed on de- 
stroyers and other submarine chasers. The ad- 
vantages and limitations of this type of gear 
are considered in great detail in the Division 6 
volumes. 

Another problem in antisubmarine warfare, 
nearly as difficult as the detection problem, is 
that of ordnance. After the submerged sub- 
marine has been located, unless one elects to 
run away, the U-boat must be rendered incapa- 
ble of launching its torpedo. The problem here 
is twofold: the choice of ordnance which will 
damage a submerged submarine and the design 
of fire control equipment which will enable the 
ordnance to be projected close enough to the 
submarine to do damage. World War I saw 


ANTISUBMARINE WARFARE IN WORLD WAR II 


11 


the development of depth charges, cans full of 
TNT which could be projected from the deck 
of a destroyer and which were provided with 
fuzes detonating at a predetermined depth. The 
“ash cans” were not streamlined to ensure an 
accurate path through the water, and fire con- 
trol equipment was almost nonexistent. The 
destroyer would drop astern a few depth 
charges at the point estimated to be above 
the submarine, and if these charges exploded 
within approximately 20 ft of the submarine's 
hull, damage usually resulted. The method of 
location was so inaccurate that several hun- 
dred depth charges had to be dropped before 
any damage might be expected to result, and 
a great number of submarines escaped un- 
scathed. 

The beginning of World War II found both 
sides relatively unprepared for the resumption 
of submarine warfare. England had only about 
200 ASDIC-fitted antisubmarine craft (com- 
pared to more than 3,000 such craft at the end 
of World War I) . The Germans, probably again 
expecting a short war, had only about 60 
U-boats, of which 30 were of the small 250-ton 
type of limited endurance. Of the 30 larger 
U-boats, 20 were of 500 tons, and 10 were of 
750 tons. These last two classes were faster 
than the U-boats used in World War I and were 
also considerably stronger, being able to dive 
deeper and to withstand more depth-charge 
punishment. The Germans had also developed 
an electric torpedo which did not leave any 
visible wake. Nevertheless, 30 ocean-going sub- 
marines were not sufficient to constitute a 
threat to England’s shipping. Neither side had 
appreciated the usefulness of aircraft in anti- 
submarine warfare, and the Germans either 
had not heard about the supersonic echo-rang- 
ing gear of the English or else had underesti- 
mated its effectiveness in locating U-boats. 

15 ANTISUBMARINE WARFARE IN 
WORLD WAR II 

Period I — September 1939 
to June 1940 

By September 1, 1939, when Germany in- 
vaded Poland, there were already six U-boats 


at sea. This time England immediately insti- 
tuted convoying, and the first convoy sailed on 
September 6. Since most of the ASDIC-equipped 
destroyers were needed to protect the Fleet, 
there were very few escort vessels available. 
Nevertheless, convoying immediately showed 
its value; for during September, while con- 
voying still was only partial, more than 900 
ships were convoyed without the loss of a single 
ship while in convoy. By contrast, during the 
month 39 unconvoyed ships of 151,000 gross 
tons were sunk by U-boats. 

The U-boat tactics at the beginning of World 
War II paralleled closely those of World War I, 
and took little or no account of the development 
of the British ASDIC gear. The U-boats pre- 
ferred attacking their targets during daylight, 
believing themselves relatively invisible because 
of their powers of submergence, while they 
could observe the targets through their peri- 
scopes. The attacks often were made by tor- 
pedoes from periscope depth, but if the target 
were an unarmed merchant vessel, U-boats 
would generally surface and attempt to sink 
the ship by gunfire. Gunfire from surfaced 
U-boats sank 10 of the 39 ships sunk during 
September 1939. This led the British to take 
steps immediately to arm defensively as many 
merchant ships as possible. 

At first, aircraft carriers were used on anti- 
submarine escort, but after HMS Courageous 
was sunk by a U-boat on September 17 the 
carriers were withdrawn. Shore-based aircraft 
of the Coastal Command, however, helped con- 
siderably by flying more than 100,000 miles in 
September, sighting some 50 U-boats (or sup- 
posed U-boats) and attacking more than 30 of 
them. Few of the aircraft attacks were very 
effective because aircraft antisubmarine arma- 
ment was undeveloped. But they did cause 
U-boats to submerge and thereby reduced the 
submarines’ effective operating period. 

The September U-boat campaign was fol- 
lowed by a lull during the first 10 days of 
October, during which hardly any ships were 
attacked, although U-boats were at sea. This 
probably reflected the current political situa- 
tion, as it was accompanied by Hitler’s offer 
of peace on October 6. U-boat activity flared up 
again on October 12, and by the end of the 


12 


THE ANTISUBMARINE PROBLEM 


month 28 ships of 136,000 gross tons had been 
sunk by U-boats. In addition, the U-boat ace, 
Prien, the commander of U-47, penetrated the 
harbor of Scapa Flow in the middle of October 
and sank the battleship HMS Royal Oak. This 
served to direct British attention to the neces- 
sity of protecting harbors against U-boats. 

During November and December the main 
effort seems to have centered on a mine-laying 
campaign off the east coast of England, par- 
ticularly in the Thames estuary. Mines laid 
were both the old-type contact mines and also 
a new type of magnetic mine, which at first 
proved difficult to sweep. Monthly losses due to 
U-boats fell to 18 ships of about 65,000 gross 
tons and were exceeded by the 100,000 gross 
tons of shipping sunk by mines during each of 
these months. 

U-boat activity began increasing again in the 
second week of January 1940 and by the end 
of the month there were as many U-boats at 
sea as at the start of the war. In February the 
U-boat effort was greater than during any pre- 
vious period and 35 ships of 153,000 gross tons 
were sunk. The U-boats continued to follow a 
policy of attacking without warning either neu- 
tral single ships or stragglers from convoys, thus 
making it difficult for the antisubmarine ships 
to make an effective search and counterattack. 
The respect U-boats had been showing for the 
British convoys is indicated by the fact that 
although roughly about half the shipping had 
been sailing in convoys during this time, only 
7 of the 169 ships sunk by U-boats during the 
first 6 months of the war were in convoy when 
sunk. 

There was a marked lull in U-boat activity 
throughout March, featured by the complete 
absence of submarines from Atlantic waters 
after about March 12. Early in April every 
available U-boat left Germany to take up patrol 
positions in the North Sea to help in the im- 
pending military operations against Norway. 
The average number of U-boats in this region 
reached a peak of about 15 during the second 
week of April when Germany invaded Norway. 
Despite the large concentration of U-boats, the 
damage done by them was remarkably small. 
No British capital ship was even attacked by a 
U-boat, and only six ships of 31,000 gross tons 


were sunk during the whole month of April. 
Germany, on the other hand, lost six U-boats 
during the month, a new high for the war. 

There was very little activity during the first 
half of May as Germany started her invasion 
of Holland and Belgium. It is believed that no 
U-boat proceeded to the western approaches 
until May 21, and only ten ships of 48,000 gross 
tons were sunk during the month. Shipping 
losses to U-boats were exceeded for the first 
time during the war by the 154,000 gross tons 
of shipping sunk by aircraft. These losses were 
incurred largely in connection with the evacu- 
ation of the British Expeditionary Force from 
Dunkirk at the end of May. 

In June, Germany recommenced her subma- 
rine campaign with increased vigor. Convoys 
were attacked with greater boldness than in 
earlier months, advantage being taken of the 
paucity of escorts, rendered inevitable by the 
demands of the military evacuation and by an 
urgent phase of surface warfare. The losses 
for June were the highest of the war with 56 
ships of 267,000 gross tons being sunk by 
U-boats. By the end of June, France was out 
of the war and Italy had entered it against the 
Allies with more than 100 submarines, about 
60 of which were ocean-going. 

In this first period, the convoy system was 
by far the most effective countermeasure in 
keeping down shipping losses, just as it had 
been during World War I. The data indicate 
that shipping was four times more likely to be 
sunk if it was not in convoy than if it was. This 
advantage of the convoy was all the more re- 
markable because most convoys at that time 
were poorly protected by escort vessels. The 
British tried to make up for the scarcity of 
escorts by keeping their convoy system flexible, 
changing the number of escorts and the dis- 
tances for which convoys were escorted in ac- 
cordance with U-boat activity. For their part, 
the Germans made the problem more difficult 
by sending the U-boats out in waves, so that 
peaks of U-boat activity occurred in September 
1939 and in February and June of 1940. 

Aircraft began to show their value in anti- 
submarine warfare in this first period, although 
their value was mainly defensive, since the 
ordnance they carried was ineffective or even 


ANTISUBMARINE WARFARE IN WORLD WAR II 


13 


nonexistent. Coastal Command aircraft flew an 
average of about 5,400 hours monthly on anti- 
submarine work. About 20 U-boats were sighted 
monthly and of these 12 were attacked, with 
about 10 per cent of the attacks resulting in 
some damage to the U-boat. This effort reached 
a peak of 9,500 hours during June 1940 when 
about 2,800 hours were spent on antisubmarine 
patrol and 6,700 hours on convoy escort duty. 

The main value of this flying was in causing 
the U-boats to submerge. This prevented 
U-boats from shadowing or approaching con- 
voys on the surface. It also helped to discour- 
age them from operating close to the shores of 
England where the flying was heaviest. U-boats 
at this time were under orders to submerge as 
soon as they sighted a plane, and the British 
took advantage of this by starting to use, in 
November 1939, light aircraft of the moth type 
in patrol around the coast. These aircraft were 
known as “scarecrows.” They carried no bombs 
and were used solely to sight and report 
U-boats, making them submerge. Their reports 
on sightings helped considerably in keeping an 
accurate plot of submarine locations. 

Surface craft equipped with ASDIC and 
depth charges were the most potent enemy of 
the U-boats during the first phase. Twenty-one 
German submarines are known to have been 
sunk as a result of Allied action during this 
10-month period. Fifteen were sunk by surface 
craft, one by the coordinated action of two 
ships and one plane, one by a plane from a 
British battleship, two by torpedoes from Eng- 
lish submarines, and two by mines while at- 
tempting to pass through the Dover mine bar- 
rage. In addition, ten Italian submarines were 
sunk in the Mediterranean, Red Sea, and Indian 
Ocean between June 10 when Italy entered the 
war and the end of the month. 

The submarine war had not reached its full 
intensity during this first period. The average 
number of U-boats at sea in the Atlantic during 
this time was about 6. The average number of 
ships sunk monthly by U-boats was 26, repre- 
senting a loss of about 100,000 gross tons. 
Therefore, during Period I about four ships of 
about 18,000 gross tons were being sunk by 
each U-boat each month at sea. At the same 
time, however, about two out of the six U-boats 


at sea were being sunk each month, so that the 
average life of a U-boat at sea was only about 
three months. Since each U-boat spent about 
one month out of three at sea, this represented 
a total commissioned life of about nine months, 
which was not bad for a naval vessel constantly 
in action against the enemy. Nevertheless the 
rate of loss was quite high, much higher than 
at any stage of World War I. 

Though the overall exchange rate of 13 ships 
of about 53,000 gross tons sunk for each U-boat 
sunk represented a fairly satisfactory bargain 
from the German point of view, the rate of loss 
of the limited number of U-boats had become 
greater than the Germans could stand. By the 
end of June 1940 despite the fact that the 
U-boats had concentrated against unescorted 
ships rather than against escorted convoys, 18 
of the original 30 ocean-going U-boats had been 
sunk, whereas only about 15 new ones had 
been commissioned, representing a net loss of 
3 commissioned units. This high rate of loss 
caused the Germans to change their submarine 
tactics during the next phase of the U-boat war. 

At the end of June 1940 England was left 
alone in the war against Germany, and her 
ability to carry on the struggle was dependent 
on her being able to keep open the sea lanes 
between herself and America. Shipping losses 
of the Allied and neutral nations were about 

280.000 gross tons monthly as compared to a 
building rate of only about 90,000 gross tons 
monthly, representing a total net loss of 

1.900.000 gross tons for the 10-month period, 
or about 5 per cent of the total Allied shipping 
available at the beginning of the war. Shipping 
losses promised to remain on the upgrade for 
some time to come. And since no method had 
yet been devised to counter the U-boat effec- 
tively, the only hope of keeping the rate of net 
loss down was to expand and accelerate the 
building of merchant vessels. This, of course, 
reduced England’s capacity to build warships, 
and later reduced the Allied capacity to build 
landing craft. 

The U-boat was definitely the main threat to 
Allied shipping, being responsible for at least 
half of the sinkings due to enemy action. Mines 
sank one-fourth of the total, aircraft one-eighth 
of the total, and surface craft and other causes 



14 


THE ANTISUBMARINE PROBLEM 


were responsible for the remaining eighth. The 
convoy system had been the main factor in 
keeping the shipping losses to submarines down 
to a moderate level. The British had nearly 
doubled their ASDIC-equipped antisubmarine 
vessels in this 10-month period, but even so the 
number of these ships that could be spared for 
escort duty was still insufficient to provide 
adequate protection. The British had been for- 
tunate during the first period in that the enemy 
had only a small number of U-boats available, 
and these had operated in a limited area, almost 
all of the sinkings of ships occurring in the 
northeast Atlantic east of 20 degrees west lon- 
gitude, and north of 30 degrees latitude. This 
had helped to make the escort problem easier 
during this first period. But to those who had 
fought the U-boat in the First World War, the 
signs were reminiscently ominous. If Germany 
could build submarines faster than England 
was sinking them, the problem would become 
serious indeed. 

1,5,2 Period II — July 1940 to March 1941 

The second phase of the U-boat war was marked 
by a complete change in submarine tactics. The 
U-boats, having discovered as a result of their 
high rate of loss that they could be located by 
ASDIC when submerged, decided to make use 
of the hours of darkness to regain their relative 
invisibility. At night, trimmed down on the 
surface, a U-boat offers a very small target to 
the human eye and is also rather difficult to 
detect by ASDIC. Acting on this principle and 
encouraged by the results achieved by the few 
attacks at night during the first period, the 
Germans began in July 1940 the general prac- 
tice of attacking convoys at night from a sur- 
faced position and then using their high surface 
speed to escape. Occasional daylight attacks 
were still made on ships sailing independently 
and on stragglers from convoys. 

Accompanying this change in the enemy tac- 
tics came the occupation of the French ports 
and their establishment as submarine bases. 
The use of these bases served to cut down the 
transit time of the U-boats and enabled them 
to extend their area of operation further west- 
ward in the Atlantic. From air bases in France 


the enemy was also able to send out long-range 
reconnaissance aircraft to pick up transatlan- 
tic convoys. Many British destroyers and air- 
craft had to be concentrated along the east and 
south coasts of England in order to repel a 
possible invasion. Consequently, just at a time 
when Germany was able to make more efficient 
use of her submarines, the English were com- 
pelled to reduce the protection of their convoys. 
In addition, all the convoys had to be routed 
around the north of England, which increased 
their time at sea. 

Increased U-boat activity, which had com- 
menced in June 1940, continued through July 
and August with more than 200,000 gross tons 
of shipping being sunk in each of these months. 
Up to the middle of July, the most active area 
was still in the western approaches between 
the latitudes of 48° N and 51° N. After the 
British convoys had been rerouted around the 
north of England, the U-boats lost no time in 
shifting their area of activity to the northwest- 
ern approaches. This activity was marked by 
increased attacks on convoys while antisubma- 
rine escorts were present. But these attacks at 
first were only on those convoys which were 
scantily guarded by only one or two ASDIC- 
fitted ships. 

The attacks increased in intensity after Au- 
gust 15 when Germany proclaimed a complete 
blockade of the British Isles. The shipping 
losses continued to increase with about 300,000 
gross tons being sunk in September and 346,000 
gross tons in October, a new high for the U-boat 
up to that date. The scene of greatest activity 
during these months was still the northwestern 
approaches, with night attacks on convoys being 
the most favored method. Of the 59 ships at- 
tacked in this area in September, 40 were in 
convoy; 70 per cent of the total were night 
attacks. The concentration of attacks into the 
period of, and immediately following, the full 
moon was especially noticeable during October, 
when 31 ships were attacked on October 18 
and 19. 

The losses resulting from this increased ac- 
tivity were a vindication of the new tactics, 
since during these 3 months the average num- 
ber of U-boats at sea was still only about six. 
This meant that ten ships of about 60,000 gross 




ANTISUBMARINE WARFARE IN WORLD WAR II 


15 


tons were sunk by the average U-boat at sea 
during October 1940, probably an all-time high 
in general effectiveness for submarines. In ad- 
dition to inflicting these heavy losses, U-boats 
were almost invariably escaping undamaged. 
In October, for instance, only one U-boat was 
sunk in the Atlantic. It is no wonder that the 
antisubmarine problem was rated high on the 
priority list of the newly formed National De- 
fense Research Committee in the United States. 

The new tactics, which were proving so suc- 
cessful for the Germans, involved shadowing 
and night attack. The individual U-boat would 
usually gain contact with the convoy during the 
day, either as a result of reports from long- 
range German reconnaissance aircraft or from 
reports from other U-boats or by direct sight- 
ing. It would then shadow the convoy at visi- 
bility distance on the bow or beam until dark- 
ness. The U-boat, trimmed down on the surface, 
would then close on the convoy and endeavor 
to reach a position broad on its bow. It would 
try to come in astern of the forward escorts 
and approach as close as possible to the mer- 
chant vessels themselves. Having reached a fir- 
ing position on the beam of the convoy, most 
U-boats would increase to full speed, fire a 
salvo of four torpedoes, turn away still at full 
speed, firing the stern tubes if possible, and 
would then retire as rapidly as possible on the 
surface in the direction considered safest. If 
their retreat was undetected, they sometimes 
reloaded their torpedo tubes on the surface and 
attacked again later in the night. 

The serious damage inflicted on British con- 
voys by these new U-boat tactics caused a num- 
ber of changes to be made in the convoy dis- 
position. The spacing of the columns of the 
convoy was opened up to reduce the chance of 
more than one ship being hit by a salvo. Escorts 
were stationed farther away from the convoy, 
and new plans were developed for searching for 
the U-boats with illumination after an attack 
had taken place. In order to improve the tacti- 
cal efficiency of the escorts, these ships were 
formed into groups and, as far as possible, 
ships of one group were to work together. 
Admiralty took over the responsibility for the 
routing of all ocean-going convoys, thus ena- 
bling emergency changes to be made without 


delay. In addition, great efforts were made to 
equip all convoy escorts with radar, which would 
enable them to locate the U-boats on the sur- 
face at night beyond visibility distance ; if pos- 
sible, before they could attack the convoy. 

Since the new U-boat tactics involved a great 
deal of wireless communication to and from 
the submarines, high-frequency direction find- 
ers [HF/DF] or “Huff-Duff” were developed 
and installed on some escort vessels. In time, 
after experience had been gained, the HF/DF 
was often capable of warning the escorts of 
an approaching attack. This proved to be ex- 
ceedingly valuable, for it was then possible to 
bring in aircraft if the convoy was close enough 
to an air base, and to strengthen the escort in 
the direction from which the attack would most 
likely come. Land-based HF/DF stations could 
fix the location of the various U-boats by tri- 
angulation, and it was not long before the 
Admiralty U-boat plot provided a fairly accu- 
rate day-by-day location of nearly all the Ger- 
man submarines on patrol. This plot proved of 
great value in deciding the routing of convoys 
and in sending additional escort strength to 
convoys which might be threatened with attack. 
The U-boat plot, with its necessarily complex 
system of news gathering, proved to be an 
immensely valuable facility in the antisubma- 
rine war. With its aid, more protective forces 
could be concentrated to meet the enemy at his 
point of greatest concentration, so that the in- 
adequate number of escort vessels could be used 
as efficiently as possible. 

With the fall of France, the Germans made 
the ports in the Bay of Biscay into bases for 
the repair and refitting of operative subma- 
rines. By November 1940, Lorient had be- 
come the principal U-boat base, with St. Na- 
zaire, Bordeaux, and other ports as subsidiary 
bases. Possession of the Bay of Biscay ports 
was a great advantage to the U-boats, since it 
not only shortened the transit time between 
base and patrol area, but also ruled out an 
effective Allied mine barrage. It might be barely 
feasible to close the exits to the North Sea by 
mines, but to blockade the Bay of Biscay was 
practically impossible. The U-boat bases in the 
Bay of Biscay were subjected to a gradually 
increasing number of bombing attacks which 


16 


THE ANTISUBMARINE PROBLEM 


seem to have been annoying to the Germans, 
but not too serious in their effects. The repair 
facilities and the U-boat docks were all put 
underground beneath huge thicknesses of con- 
crete. After the capture of these ports in 1945, 
it was discovered that only one or two bombs 
had ever penetrated the concrete defenses into 
the U-boat docks. 

For the time being, all the British could do 
to counter these new and serious attacks on 
convoys was to improve the use of the antisub- 
marine gear they had on their escort vessels 
by continuous refresher training and to per- 
fect their counterattack tactics. In November 
1940, three U-boats were sunk while they were 
attacking convoys. This minor success might 
account in part for the reduced number of at- 
tacks on escorted convoys in November and 
December 1940. Heavy winter weather in the 
North Atlantic was more probably a factor in 
accounting for the decrease in shipping losses 
to U-boats. Only 150,000 gross tons were sunk 
by U-boats in November, and 200,000 gross 
tons in December. Parenthetically, it might be 
noted how serious the matter had become when 
the word “only” can be used in connection with 
these tonnages lost. 

The Coastal Command increased its antisub- 
marine flying out from England, and the air- 
craft attacks on submarines became somewhat 
more lethal. Partly on this account, early in 
December, a westerly movement of the U-boats 
became noticeable, with most of them patrol- 
ling as far out as 20° W longitude. This west- 
erly movement may also have been due to an 
attempt to intercept incoming convoys before 
the heavy antisubmarine escorts joined them. 
As a matter of fact, however, patrolling so far 
from the focal points of convoy routes made it 
considerably more difficult for the U-boat to 
find the convoys and considerably easier for the 
English to route their convoys evasively. The 
advantages of a complete and accurate U-boat 
plot became more apparent to the English. 

In December 1940, maximum evasive routing 
of convoys was tried by the British. The routes 
of convoys were spread between 64° and 57° N 
latitude, and the cycles of convoys were also 
opened out with the object of reducing the 
strain on escorting forces. This thorough 


spreading of convoy routes seems to have been 
a main factor in the reduction of shipping 
losses, just as it had been in World War I. No 
attacks were made on escorted convoys from 
December 2, 1940 until January 29, 1941, and 
the losses due to U-boats in January dropped 
to 21 ships of 127,000 gross tons, the lowest 
figure since May 1940. This occurred despite 
the fact that the average number of U-boats at 
sea in the Atlantic had increased to about 12. 
Most of the ships lost were not in convoy, since 
the U-boats went back to the much easier task 
of picking off stragglers or independents. 

The month of February 1941 opened with a 
continuation of the comparative lull in U-boat 
activity. This lull, however, was due to the 
Germans’ preparation for new tactics, the “wolf 
pack.” The obvious answer to wide evasive 
routing of convoys was increased cooperation 
between U-boats, utilizing high-frequency wire- 
less intercommunication, and handling the sub- 
marines more and more as surface raiders 
which submerged only when under attack. The 
U-boats began operating in groups of three to 
five, each U-boat being given a limited patrol 
area within the wider area covered by the 
group. The first U-boat to gain contact shad- 
owed the convoy, while other U-boats were 
ordered to close in, homing on the radio signals 
given out by the shadowing U-boat. At times, 
aircraft were used to home U-boats on a convoy. 

Cooperation between U-boats, aircraft, and 
surface craft is well illustrated by the attack 
on the convoy, HG-53, consisting of 21 ships 
escorted by one sloop and one destroyer. The 
convoy was attacked by a U-boat early on 
February 9, two ships being sunk. The U-boat 
continued to shadow the convoy and probably 
homed six Focke-Wulf aircraft to it during the 
afternoon of February 9. Five ships were 
bombed and sunk while one plane was shot 
down. The U-boat continued to shadow the con- 
voy and again attacked successfully, sinking 
one ship. After this she maintained touch with 
the convoy, reporting its position. Her reports 
were evidently intended for a German Hipper 
class cruiser. While closing HG-53, however, 
this cruiser came upon the unescorted slow 
portion of another convoy and attacked this 
target instead, sinking seven ships. 


ANTISUBMARINE WARFARE IN WORLD WAR II 


17 


Three other convoys were attacked by U-boats 
in the last week of February, and as the month 
drew to an end, with the losses to U-boats 
amounting’ to 36 ships of 190,000 gross tons, 
it was evident that the expected spring offen- 
sive had commenced. The average number of 
U-boats at sea in the Atlantic rose to 16 in 
March. Their tactics included a repetition of 
the concentrated night attack upon convoys, 
and six convoys were attacked during the 
month. Losses were still higher in March, being 
40 ships of 240,000 gross tons. These losses, 
however, were considerably less than those dur- 
ing the previous September and October, and 
since there were twice as many U-boats at sea 
in March as in September, the situation was 
not yet regarded as critical. 

As a matter of fact, the antisubmarine escort 
vessels were becoming increasingly efficient at 
using their supersonic echo-ranging gear and 
in conducting antisubmarine attacks. One after 
the other of the outstanding “U-boat aces” of 
the early part of the war was sunk or captured 
about this time. This seems to have made the 
Germans somewhat more cautious, for, during 
the last week in March, activity slackened some- 
what. 

During this second period of the U-boat war, 
the British were learning how to use aircraft 
against submarines. They were learning that 
the plane is extremely valuable in finding sub- 
marines, as long as the U-boat tactics are to 
stay on the surface most of the time. A U-boat 
on the surface is fairly certain of seeing an 
enemy ship before she herself is seen. This is 
not true of aircraft and a fairly large number 
of U-boats were unpleasantly surprised by hav- 
ing aircraft swoop down and drop depth charges 
before they had had any warning at all. This 
was an unsettling experience, even though it 
was not at first very dangerous. 

It had already been realized that ordinary 
general-purpose bombs were of very little use 
against submarines, and Coastal Command had 
begun using naval depth charges modified for 
use from aircraft. They began in July 1940, 
and on August 16 their first success was scored 
when a U-boat was severely damaged as a re- 
sult of a depth-bomb attack. On the first run-in, 
the U-boat, which was submerging rapidly, was 


blown to the surface to be further damaged 
by subsequent run-ins. In view of this success, 
steps were taken to modify all Coastal Com- 
mand aircraft in order to enable them to carry 
depth charges. A considerable amount of study 
was made to determine the best depth setting 
for these charges. At first the setting was 50 to 
75 ft or deeper. It was realized later, however, 
that most of the attacks were being made on 
submarines surfaced or near the surface, so 
that a 25-ft setting would be more lethal. This 
was subsequently adopted. 

By the fall of 1940 a few Coastal Command 
aircraft were being fitted with radar of the 
long-wave type. It was hoped that this would 
eventually enable the aircraft to be used against 
submarines at night as well as on days of poor 
visibility. With the developing U-boat tactics 
of shadowing by day and running in to attack 
by night, it was important that the rear and 
flanks of the convoy be searched thoroughly at 
evening. It was hoped that radar-equipped air- 
craft could help in this task. 

After the evasive routing of shipping had led 
to the start of wolf-pack tactics in February 
1941, the early detection of the shadowing 
U-boat became the main problem. Having 
gained contact with the convoy, the U-boat took 
great care not to reveal its presence by attack- 
ing in daylight, but shadowed the convoy at 
some distance. There was, therefore, only a 
small chance of the surface escort discovering 
or attacking these U-boats, and the task fell 
more and more on the escorting aircraft. Con- 
sequently the number of Coastal Command air- 
craft available for escort duty was increased. 
The average number of hours flown monthly by 
Coastal Command aircraft on antisubmarine 
duty increased to about 6,300 hours per month, 
5,100 hours being on convoy escort and 1,200 
hour§ on general patrol. The number of flying 
hours on antisubmarine work dropped to about 
4,000 hours during the winter months of De- 
cember 1940 and January 1941, because of the 
poorer weather. By March 1941, however, it 
was back up to about 8,000 hours per month. 
This increased amount of flying was partly the 
cause of the U-boats’ leaving the near shores 
of the British Isles and extending their activi- 
ties farther westward. As a result of the move- 


18 


THE ANTISUBMARINE PROBLEM 


ment of the U-boats, the antisubmarine flying 
of Coastal Command became less productive of 
submarine sightings and attacks. By March 
1941 the number of sightings made monthly 
was only about 14, and the number of attacks 
was about 8. As before, only about 10 per cent 
of the attacks resulted in some damage to the 
U-boat, but now that depth charges were being 
used about 2 per cent of the 10 per cent repre- 
sented probable sinkings of U-boats. The lethal- 
ity of the aircraft against the submarine was 
slowly increasing. 

To help in locating the shadowing submarine, 
which was sending out radio signals to allow 
the other U-boats to home on it, the HF/DF 
sets mentioned earlier were rapidly developed 
and installed on escort vessels. A carefully con- 
structed and continually manned land-based 
network indicated the location of every radio 
transmission from the Atlantic. The combina- 
tion of shore- and ship-based HF/DF was soon 
so good that it was possible to estimate the 
danger of attack on a convoy with some accu- 
racy. Thus it was possible to send Coastal Com- 
mand aircraft only to threatened convoys, 
thereby providing an immense saving in effort. 

The chief scientific improvement in antisub- 
marine defenses introduced during this period 
was the radar set for ships and aircraft. The 
sets were crude according to present standards, 
and their efficient use was not yet well under- 
stood. Nevertheless these sets enabled attacks to 
be made on submarines which could not have 
been carried out otherwise. They were particu- 
larly valuable during this phase when the 
U-boat attacks were mostly at night, although 
the results from the first installations on escort 
vessels were disappointing to their designers. 
The effective ranges on submarines were very 
much less than had been expected, and a great 
deal of interference was encountered because 
of the presence of the convoy. Nevertheless, the 
sets gave a measure of protection during the 
night, and immediate steps were taken to im- 
prove the range by increasing the directionality 
of the antennas. 

During this second period, surface craft con- 
tinued to be the most effective weapon in at- 
tacking and sinking U-boats, making about 25 
attacks a month. Of the 23 U-boats sunk, or 


probably sunk, in the Atlantic during this pe- 
riod, surface craft could be credited with 13. 
Allied submarines continued to be highly effec- 
tive early in the period, patrolling close to the 
French bases and torpedoing five U-boats in 
September 1940 and one in December. These 
submarine attacks made it necessary for the 
U-boats to enter and leave their bases sub- 
merged. Two U-boats were probably sunk as a 
result of aircraft attacks and one was sunk as 
a result of a combined attack by ship and plane. 
One submarine was lost to a mine. 

In the Mediterranean, 11 Italian U-boats were 
sunk in Period II, with surface craft accounting 
for 6 of them. Italian submarines, in all, had 
very little success against Allied shipping. Only 
5 ships of 28,000 gross tons were sunk in the 
Mediterranean and the Indian Ocean during the 
first two years of the war. 

When all the returns were in, it could be 
seen that this second period had resulted in 
somewhat of a draw between convoys and sub- 
marines. The new U-boat tactics adopted had 
accomplished their primary objective of reduc- 
ing the high rate of loss of U-boats. The aver- 
age number of German submarines at sea in 
the Atlantic during the period rose to about 10, 
while only about 21/2 of these were lost monthly. 
The average life of a U-boat at sea, therefore, 
increased from three to four months. In addi- 
tion, the efficiency of U-boats in sinking ships 
had increased slightly, since the average U-boat 
sank four ships of 22,000 gross tons per month 
at sea. This resulted in an increase in the over- 
all exchange rate for submarines to 16 ships 
of about 88,000 gross tons sunk for each U-boat 
sunk or probably sunk; representing a fairly 
profitable transaction for the Germans. 

On the other hand, the Germans had suffered 
considerable losses early in the period, losing 
many of their ablest and most experienced 
U-boat captains and crews, who were not so 
easily replaced as the U-boats themselves. The 
necessity of sending out relatively inexperi- 
enced U-boat captains was probably a factor 
influencing the Germans in February 1941 to 
inaugurate wolf-pack tactics, so that several 
inexperienced U-boat captains could operate 
with a more experienced one. 

Total Allied shipping losses during Period II 




ANTISUBMARINE WARFARE IN WORLD WAR II 


19 


were about 456,000 gross tons a month, more 
than 60 per cent higher than during the first 
period. Meanwhile the building rate had in- 
creased only slightly to about 114,000 gross tons 
a month. Total shipping available had been 
reduced from about 38,000,000 gross tons at 
the start of the second period to about 35,000,- 
000 gross tons at the end. Of the 456,000 gross 
tons of shipping lost monthly, the U-boat ac- 
counted for 42 ships of 224,000 gross tons a 
month on the average, more than twice the 
monthly tonnage sunk by U-boats during the 
first period. Losses due to enemy surface craft 
and to enemy aircraft increased somewhat, and 
losses due to mines dropped to a negligible 
amount. 

There is no doubt that the U-boats had in- 
flicted a serious loss to the Allies during this 
second period ; but the situation was beginning 
to look more promising toward the end. One 
favorable element was the increasing number 
of antisubmarine ships and aircraft becoming 
available for convoy escort. New ships and 
planes were being built and since the threat of 
invasion to England was decreasing, other ships 
could be assigned to fight the U-boat. The num- 
ber of antisubmarine ships suitable for ocean 
escort had increased from about 235 at the start 
of the second period to about 375 at the end. 
A new type of escort vessel, the corvette, was 
I coming into use, and the United States trans- 
ferred to the British 50 old-type destroyers 
which were of considerable value. All these de- 
stroyers were equipped with U.S. echo-ranging 
gear. Ships and planes were being fitted with 
radar as fast as possible. 


1 ' 5 ' 1 * 3 The Situation in the Spring of 1941 

This was the situation in the spring of 1941 

when NDRC commenced its work on the de- 
velopment of antisubmarine equipment. The 
U-boats, with their newly developed pack tac- 
tics, were showing themselves to be even more 
dangerous than in World War I. In 1940, Ger- 
many had begun to realize that this was not to 
be a short war and had considerably increased 
the program of U-boat building. These new 
U-boats were beginning to becomo operational 


in 1941; and by the end of the year they had 
about 200 ocean-going submarines, and new 
units were being commissioned at the rate of 
about 20 a month. Many of the veteran crews 
and commanders had been killed, but the group 
tactics enabled comparatively inexperienced 
U-boat crews to be used fairly effectively. Suc- 
cessful attacks were being made on convoys, 
although the submarines still preferred attack- 
ing independent shipping, as the United States 
discovered to its considerable cost in the next 
year. 

The most important protection against 
U-boats was still the convoy. During the sum- 
mer of 1941, the submarines’ wider distribution 
over the Atlantic forced the British to escort 
their convoys clear across the Atlantic, and by 
the end of 1943 complete escorting of all Atlan- 
tic convoys, including coastal shipping along 
the eastern seaboard of the United States, had 
been adopted. By the middle of 1941, all ship- 
ping of less than 15 knots speed, which was 
crossing the Atlantic, was required to sail in 
convoy. 

An analysis of the convoys during the sum- 
mer of 1941 gives information about the “aver- 
age attacked convoy.” On the average the con- 
voy was attacked by 4.2 U-boats of which 2.6 
succeeded in delivering effective attacks. A total 
of 4.6 ships in the convoy were torpedoed, 1.7 
ships being torpedoed in each effective attack. 
Of the 4.2 U-boats engaging the convoy, 3.2 
were attacked by the air and surface escort, and 
0.7 were sunk or probably sunk. 

The value of aircraft in antisubmarine work 
was beginning to be realized. Aircraft had 
primarily been responsible for forcing these 
U-boats away from the British shores. In the 
summer of 1941, the effective lethality of air- 
craft attacks on U-boats was considerably im- 
proved by changing the attack tactics to con- 
form to the fact that most of the effective 
attacks were against surfaced submarines. By 
the end of the summer the lethality of aircraft 
attacks had increased considerably, about 25 
per cent of the U-boats attacked by aircraft 
being damaged. During the summer and fall of 
1941, a determined air campaign was begun 
against the U-boats moving in and out of the 
Bay of Biscay. By September 1941, each U-boat 


20 


THE ANTISUBMARINE PROBLEM 


was being attacked in the bay on one of every 
three transits of this area. This was a sufficient 
menace to force them to remain submerged in 
the bay during daytime, which increased their 
transit time considerably. 

By the end of 1941, Coastal Command had 
commenced the experiment of using aircraft at 
night against U-boats. These aircraft, fitted 
with radar and searchlights, were to prove a 
greater and greater menace later in the war. 

Attempts were also being made to improve 
the antisubmarine ordnance for surface vessels. 
The “hedgehog” device for throwing a number 
of small contact charges ahead of the vessel 
was being introduced. This did not immediately 
prove successful, but it represented a realiza- 
tion that surface craft antisubmarine ordnance 
must be improved. 

A complete discussion of antisubmarine war- 


fare during World War II is given in another 
volume. b Enough is included here to make it 
apparent why the study of antisubmarine meas- 
ures was considered by NDRC to be of top 
priority. Allied shipping was being lost at a 
dangerous rate. If the losses were not reduced 
quickly, the whole progress of the war in 
Europe would be endangered; and Allied ship- 
yards, instead of being able to add importantly 
to the force of warships, would be compelled to 
devote most of their facilities to making up, 
or trying to make up the losses in merchant 
ships. It was time for the trying out of all sorts 
of defensive weapons and measures, to see 
whether some new or improved detection gear 
or weapon might not be the answer. A re-evalu- 
ation was urgently needed. 


b Division 6, Volume 3. 


4 


Chapter 2 

SCOPE OF DIVISION ACTIVITIES 

By Edwin H. Colpitis 


W hen scientific aid in preparing for and 
conducting subsurface warfare was first 
envisaged through NDRC, it was felt that this 
aid should take the form of improving and de- 
vising equipment and methods for detecting 
submerged enemy submarines from surface 
ships. But the group (later to be identified as 
Division 6) had scarcely been organized when 
it was realized that the field of its responsibility 
as first defined was too narrow. 

The unique feature of Division 6 was that its 
ultimate responsibility was not to develop a 
particular instrumentality of war or to exploit a 
particular field of science for military purposes 
but was to assist the Navy in all ways in which 
men of scientific and engineering experience 
and skill could significantly contribute to the 
prosecution of subsurface warfare. Thus, as the 
subsurface warfare group began to work, it be- 
gan to grow and assume added responsibilities. 
To detection from surface craft was added detec- 
tion of submarines from aircraft. The develop- 
ment of equipment and devices, first confined 
to instruments of detection and location, came 
to include ordnance and decoys. The program 
of physical research quickly reached out in 
numerous directions to acquire information 
basic to the development and use of better gear. 
The need for operational analysis and research 
soon led to the establishment of a specialized 
unit; similar needs for aid to the Navy in the 
selection and training of personnel and the 
installation and maintenance of equipment led 
to the formation of other special divisional 
groups. As the character of subsurface war 
changed, the division turned more and more 
from a program designed to further the anti- 
submarine effort to one aimed at aiding our 
own submarines. 


in the previous chapter. It was a situation which 
had grave implications for the United States 
which once again was confronted with a tre- 
mendous problem of sea logistics. 

Certain steps had already been taken. In 
December 1940 a subcommittee of the Naval 
Advisory Committee of the National Academy 
of Sciences was organized to analyze this coun- 
try’s ability to fight a successful submarine 
war with existing equipment and tactics and 
to make recommendations how best to employ 
the scientific and technical talent available to 
improve our preparedness. 

This preliminary analysis, concerned only 
with the detection and location of submarines 
from surface craft, pointed out that although 
the supersonic echo-ranging gear developed by 
the Naval Research Laboratory in cooperation 
with the Submarine Signal Company was capa- 
ble of good performance, the quality and train- 
ing of Navy sound operators left much to be 
desired. Also, the lack of understanding of ir- 
regularities in the performance of the equip- 
ment urged the formation of a broad program 
of research in the fundamentals of underwater 
acoustics. 

Shortly thereafter the Navy formally re- 
quested NDRC to set up a special group to 
undertake further studies and developments. 
This request was promptly acted upon and Sec- 
tion C-4 was created to develop new and im- 
proved means for detecting submerged subma- 
rines. The group continued its activities as 
Section C-4 until the creation of OSRD after 
which it became Division 6. 


2 2 FORMULATION OF A PROGRAM 
Equipment 


21 FORMATION OF SECTION C-4 Enough of the NRL echo-ranging equipment 

had been produced and installed on ships to 
The serious situation facing the Navy and enable some determination of its capabilities as 

NDRC in the spring of 1941 has been outlined well as its limitations. This was supported and 


21 


22 


SCOPE OF DIVISION ACTIVITIES 


amplified by data covering British experience 
with quite similar ASDIC gear under actual 
combat conditions. This background of infor- 
mation indicated definite steps which should be 
taken to improve the performance of the equip- 
ment and to secure its more effective use. 

Some of these steps had already been taken. 
Both the British and American Navies were 
experimenting with new projector housing or 
“dome” designs to permit echo ranging at 
higher ship speeds. The British had also de- 
veloped an improved range recorder which 
could be adopted with very little change. How- 
ever, other modifications were suggested which 
appeared likely to improve the overall perform- 
ance by reducing the level of operator skill 
necessary for satisfactory operation and in- 
creasing the speed and ease of operation. 

Because of the time elements involved in the 
development, design, production, and introduc- 
tion into Service use of any radically new equip- 
ment it was apparent that if war came it must 
be fought, possibly through its most decisive 
period, with instrumentalities already avail- 
able. The matter of greatest urgency, therefore, 
was to improve the effectiveness of existing 
designs. 

For this reason only, all proposals for modi- 
fications were carefully examined and rejected 
unless they appeared to have a good chance of 
meeting these requirements of time and ap- 
plicability. 

A more basic attack was made on the echo- 
ranging problem by two of the division labora- 
tories which led to the development of two 
scanning sonar systems. It was realized when 
undertaken that these were long-term projects 
which might not find actual employment unless 
the war was very much prolonged. Both sys- 
tems, however, including the XQHA and the 
QLA, reached the stage of prototype construc- 
tion during the course of the war. As a matter 
of interest it is understood that a number of 
sets employing one of these methods were in- 
stalled on fleet-type submarines and very effec- 
tively employed late in the war for a critical 
operation in the Sea of Japan. 

Further development of these systems to pro- 
vide increased range, depth angle determina- 
tion, and increased flexibility of application was 


under way when the laboratory programs were 
terminated. These projects are being continued 
by permanent naval laboratories, and it is an- 
ticipated they will ultimately result in the pro- 
duction of highly useful systems for both sur- 
face and subsurface service. 

Aircraft were obviously destined to play a 
most important role in the war against the sub- 
marine. It soon came to be realized that, to 
make aircraft fully effective, their ability to 
detect and attack surfaced submarines should 
be supplemented by means for detecting and 
attacking submarines after submergence or 
when submerged. As will be described in this 
report, most energetic efforts were made by 
the division to render aircraft more effective 
both with respect to means for detecting or 
locating the submarine, and with respect to 
ordnance for its destruction. These endeavors 
resulted in the development of the magnetic 
airborne detector [MAD], the radio sono buoy 
[DRSB and ERSB], and of a highly secret 
mine, all of which found effective employment 
in combat. 

Fundamental Research 

It was fully realized that any basic improve- 
ment in either equipment design or operating 
doctrine must be based upon a clearer under- 
standing of the physical principles involved. The 
fundamental importance of such knowledge to 
the entire effort of the division warranted the 
establishment of a broad research program in 
underwater acoustics and oceanography. In- 
cluded in the scope of this activity were theo- 
retical and experimental investigations of 
sound transmission, reverberation, reflection, 
and refraction. 

Data made available by these studies not only 
provide information for equipment design but 
also apply directly to operations. Echo-ranging 
efficiency is peculiarly dependent upon water 
conditions. To employ echo ranging most effec- 
tively, therefore, these varying water condi- 
tions must be thoroughly understood by those 
who would attempt to lay down operating doc- 
trine or prescribe operating practice. The same 
knowledge of underwater sound transmission 
is required in formulating and operating the 
training program for sound personnel, in order 




FORMULATION OF A PROGRAM 


23 


that operators and officers may appreciate the 
possibilities and limitations of their equipment 
and be trained to meet the various sound con- 
ditions they will surely encounter. 

Closely related to the above research effort 
was the immediate effort devoted to developing 
and standardizing means and methods for 
sound measurements. This latter program, 
among other results, enabled those designing 
and producing sound gear for the Navy to de- 
termine in a common language the efficiency 
of their product and often indicated permis- 
sible modifications by which its performance 
could be improved. 

As the scope of the division increased, fur- 
ther important researches were undertaken in 
the fields of piezoelectricity and magnetostric- 
tion theory and practice which yielded greatly 
improved transducers. Also, fundamental 
studies in fluid dynamics led the way to im- 
proved torpedoes and other projectiles. 

Operations Research 

A step most important to securing effective 
use of gear and methods was the establishment 
of the Operations Research Group. The activi- 
ties of this group concerned all operational 
aspects of antisubmarine warfare including 
methods not otherwise the concern of Division 
6. Not only did the studies of the Operations Re- 
search Group enable available gear to be used 
more effectively, but these studies were also 
important in indicating deficiencies in the 
operation or design of equipment under actual 
conditions of war. With this information, intel- 
ligent action could be taken in accurately speci- 
fying desirable functions to be provided by 
modified or new gear. 

Selection and Training of Personnel 

The British had already found that the effec- 
tiveness of sound personnel under combat con- 
ditions was very dependent upon the amount 
and adequacy of their training. This fact was 
also fully recognized by the U. S. Navy. As an- 
other step toward effective use of already avail- 
able gear, the division complied with the Navy's 
request for assistance in selecting and training 
sound operators. Later on the program was 
broadened to include other personnel as well. 


Under the general supervision of a special 
committee appointed by the division, direct as- 
sistance was given in Navy schools, operating 
bases, and other establishments in the selection 
and training of sonar operators, officers, and 
attack teams. A large number of training aids 
and classroom demonstrators constructed by 
the several laboratories supplemented this pro- 
gram effectively. 

The division feels that the contribution it 
was able to make in assisting the Navy with its 
task of selecting and training operating per- 
sonnel significantly aided the final success 
achieved in both the Atlantic and Pacific areas. 

Torpedo Program 

The division’s program for torpedo research 
included the study and development of sound- 
controlled underwater missiles, power plants 
for electrically propelled torpedoes, and basic 
design considerations relative to a torpedo 
capable of being dropped from a high-speed 
plane. 

Most of the division’s subsurface ordnance 
research was directed towards modifying and 
improving existing torpedoes. Although the ap- 
plication of acoustic homing control was under- 
taken with considerable skepticism, the division 
was successful in developing sound controls for 
both slow-speed and high-speed torpedoes. The 
air-launched, acoustically controlled antisub- 
marine Mark 24 played a very real role in con- 
trolling and eliminating the U-boat menace. 
The submarine-launched Mark 27 was designed 
as a prosubmarine weapon for use during eva- 
sion maneuvers, but it was actually used as an 
effective offensive weapon. The division also 
developed echo-ranging homing control for both 
ship-launched and air-launched torpedoes 
which performed satisfactorily in field tests. 

The fundamental studies and design work 
relative to a torpedo capable of being dropped 
from a high-speed plane were embodied in ex- 
perimental structures, but the war ended be- 
fore actual production was begun. 

Important projects relating to power plants 
for electrically propelled torpedoes included the 
development of high-capacity sea-water bat- 
teries and an efficient counterrotating motor. 
These are expected to make possible much 


24 


SCOPE OF DIVISION ACTIVITIES 


quieter operation which is significant in the ap- 
plication of acoustic homing control. Also in- 
cluded was the provision of a maximum 
range and speed equivalent to the present steam 
turbine torpedo. These developments produced 
promising results, but they were not applied to 
torpedoes in combat use. 

Prosubmarine Activities 

Although the division’s effort for perhaps the 
first year and a half was almost wholly related 
to antisubmarine warfare, it became increas- 
ingly clear that there were possibilities of as- 
sisting our own submarines in their operations 
both by development of certain gear and in 
training of personnel. 

A prosubmarine committee was organized 
which established and maintained close contact 
with the submarine forces in both the Atlantic 
and the Pacific, supplementing the established 
liaison with COMINCH and the Bureaus. Upon 
their recommendations a major effort was de- 
voted to an increasing number of prosubmarine 
activities. 

Results of this quite comprehensive program 
made available to the submarine forces im- 
proved listening and echo-ranging gear, new 
instruments to assist escape from depth-charge 
attack, special noisemakers and submarine- 
simulating decoys designed to distract or mis- 
lead enemy efforts at detection, as well as cer- 
tain ordnance devices and assistance in train- 
ing and maintenance. 

Field Engineering 

A step which perhaps should have been taken 
earlier in order to secure the optimum perform- 
ance possible with existing or new equipment 
was assistance to the Navy in maintenance. Al- 
though certain maintenance work had been 
done earlier, the opportunity to provide direct 
assistance to the Navy only became evident 
when new types of gear were being introduced. 
As a result of the large number of ships being 
fitted for ASW duty and the scarcity of ade- 
quately trained and experienced personnel, the 
ASW gear was frequently found to be faultily 
installed or in poor adjustment. To solve these 
problems, the Bureau of Ships requested the 
division to organize and train a group of ex- 


perienced engineers to be assigned for duty at 
Navy yards and bases and with the forces afloat 
to assist in the setting up of proper mainte- 
nance procedures. The scope of the Field Engi- 
neering Group’s work was eventually broad- 
ened to include assistance to the Navy in in- 
stalling and operating new gear, training per- 
sonnel, and exchanging information between 
Navy personnel and the laboratories. 

Facilities 

To implement the broad program objectives 
undertaken, the division found it necessary to 
set up a number of special laboratories and 
groups in addition to the existing facilities. 
These were both academic and commercial and 
were secured by contract. Although fullest rec- 
ognition should be given to the numerous con- 
tributions made by these organizations, their 
very number prohibits their inclusion in this 
chapter. An attempt is made in the next chap- 
ter, however, to list and describe the principal 
organizations and groups that participated in 
the division programs. 


23 CONCLUSION 

The OSRD and NDRC were established to 
meet a war emergency and consequently it was 
always understood that their operations would 
terminate as the end of the war approached. 
The termination involved the transfer of activi- 
ties from Division 6 support and direction to 
Navy support and direction. Plans which op- 
erated very effectively were worked out co- 
operatively among the Navy, the division, and 
the division’s contractors. In a substantial num- 
ber of cases the Navy was able to take over 
either completely or in large part the going 
organization which the division had built up, 
thus assuring continuity of work in these cases. 
These transfers, made during 1945, adequately 
provided for any activities which seemingly 
should be continued longer, and it is believed 
that they were accomplished at a wisely chosen 
time. 

In large measure, the very serious losses to 
U-boats sustained during the early years of the 
war were due to the lack of ships, equipment, 




CONCLUSION 


25 


and trained personnel, rather than to a lack 
of technical preparedness. In many cases, how- 
ever, serious deficiencies in equipment and tac- 
tics were uncovered by the application of the 
principles of objective analysis. Perhaps the 
division’s greatest contribution was its assist- 
ance in organizing and supporting an effective 
Operations Research Group to study scientifi- 
cally the operational requirements of the Navy. 
On the basis of knowledge thus gained and be- 
cause of the close cooperation given by the 
Navy in providing facilities and helpful liaison, 
it became possible to plan a realistic and di- 
rectly useful program of equipment develop- 
ment. Experience shows that if this close co- 
operation of the Navy and civilian scientists 
realized during World War II had been pos- 
sible between the wars, both the Navy and its 
civilian assistants would have been better pre- 
pared to meet the emergency when it arose. 

Although it is very clear that certain basic 
physical research and possibly certain equip- 
ment development should be continued, the ex- 


perience of the division suggests that an in- 
creased emphasis should be placed upon proc- 
esses which can lead to more clearly defined 
program objectives. 

To achieve future preparedness and perfec- 
tion in the operation of a system of men and 
equipment, such as in subsurface warfare, per- 
formance must be continually analyzed in the 
light of new requirements of the Navy and new 
developments in science. Those in charge of the 
program must continually study the analysis 
and apply information thus gained to the per- 
fection of the system. This kind of work re- 
quires the closest cooperation between Navy 
staffs and civilian scientists in industry and 
academic life. The men in charge of the plan- 
ning program must be closely in touch not only 
with Navy operations but also the scientific life 
of the nation. Only in this way will they be able 
to direct a balanced program of research, de- 
velopment, and improvement which will assure 
continued readiness for future subsurface war- 
fare. 


Chapter 3 

ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 

By Elmer Hutchisson 


EARLY ORGANIZATION AND 
GENERAL PROGRAM 


Introduction 

A lthough the first official act in connection 
- with the formation of a section of NDRC 
on antisubmarine warfare was a letter a dated 
April 10, 1941, from Rear Admiral S. M. Robin- 
son to Dr. V. Bush, Chairman of NDRC, re- 
questing that NDRC undertake a study of the 
problem of submarine detection, there were 
several preliminary steps which deserve men- 
tion. 

The “Colpitts Committee” 

Some six months previous to this letter, the 
National Academy of Sciences, at the request 
of the Navy, had appointed a committee, b under 
the chairmanship of Dr. E. H. Colpitts, “to 
study the scientific aspects of protection 
against submarine warfare,” and to “ascertain 
the degree and adequacy of the present effort.” 
This committee recommended that an immedi- 
ate and intensive program of investigation of 
all phases of the problem of submarine warfare 
be undertaken. Following the submission of 
this report, several discussions were held by 
various officers of the Navy, with Dr. Bush, 
Chairman of the National Defense Research 
Committee, and with Dr. F. B. Jewett, Presi- 
dent of the National Academy of Sciences. Both 
Dr. Bush and Dr. Jewett had been asked to ap- 
pear before the general board of the Navy to 
make recommendations regarding the best type 
of organization for such a comprehensive study 
of the submarine problem. 

Dr. Bush and Dr. Jewett assured the Navy 
that both NDRC and the National Academy of 

a See Appendix A. 

b Members of this committee were: W. D. Coolidge 
V. O. Knudsen, L. B. Slichter, H. G. Knox, Secretary’ 
and E. H. Colpitts, Chairman. 


Sciences were prepared to do everything that 
was necessary to get under way, as soon as pos- 
sible, a broad program of research in the anti- 
submarine field. 

Coordination with British Effort 

In 1940, at the time that the National Acad- 
emy report to the Navy was being made, a Brit- 
ish Commission in this country under the lead- 
ership of Sir Henry Tizard, recommended the 
sending of one or two civilian scientists to Eng- 
land to confer directly with scientists of the 
Admiralty on the work which was being done 
in Great Britain on the detection of sub- 
marines. In January 1941, this recommenda- 
tion was repeated by Dr. R. H. Fowler of the 
British Central Scientific Office. The proposal 
was discussed with high-ranking naval officers 
and it seemed best that two men be sent under 
NDRC auspices. Accordingly, Dr. Bush re- 
quested Dean John T. Tate of the University of 
Minnesota, and Professor Slichter of the Mas- 
sachusetts Institute of Technology to visit 
Great Britain to confer with the British scien- 
tific people on what they were doing in sub- 
marine detection, with a view to supplementing 
the information which our Navy had obtained 
through their contacts. Doctors Tate and Slich- 
ter left for England on April 7, 1941. 


Plan of Organization 

Thus, when Admiral Robinson, on April 10, 
1941, requested NDRC to undertake an investi- 
gation of the problem of submarine detection, 
preliminary negotiations had already been 
made. It was clear that this work in NDRC 
should be undertaken in Division C, which was 
under the chairmanship of Dr. Jewett. It was 
clear also that a vice-chairman should be ap- 
pointed to correlate all work in this field. It 
seemed desirable not to disturb any of the work 
already going on in other NDRC divisions that 


26 




27 


EARLY ORGANIZATION AND GENERAL PROGRAM 


might be applicable to the detection of surfaced 
submarines, and to confine the work of the new 
subdivision to the detection of submerged sub- 
marines. 

Dr. Jewett, in consultation with Dr. Bush, 
prepared a memorandum 0 proposing a definite 
form of organization which would have the fol- 
lowing objectives. 

1. The most complete investigation possible of all the 
factors and phenomena involved in the accurate detec- 
tion of submerged or partially submerged submarines 
and in antisubmarine devices. 

2. The development of equipment and methods for 
use of promising means for detection to the point where 
their final embodiment in form satisfactory for naval 
operation can be undertaken by the regular bureaus of 
the Navy. 

This plan further outlined the facilities 
which would be required. 

In Dr. Jewett's proposed plan, he stated that 
NDRC could assist primarily in organizing the 
scientific work, in locating personnel, and in 
making necessary contracts with academic, in- 
dustrial, and other institutions. To be success- 
ful, however, the Navy should provide special 
laboratory facilities, marine facilities, and nec- 
essary personnel for operating them and for 
policing the establishment, and, in general, take 
complete responsibility for the nonscientific op- 
eration of the laboratory. 

It was recommended that two central labora- 
tories should be provided, one on the Atlantic 
coast, which, because of the close liaison that 
could be maintained with Washington, would 
be concerned primarily with the final stages of 
research and development; and the other on 
the Pacific coast, charged primarily with carry- 
ing to completion fundamental research work 
in fields applicable to antisubmarine warfare. 
For the scientific work of the Atlantic coast 
laboratory, NDRC would provide a director 
who had had long industrial experience. For the 
scientific work at the Pacific coast laboratory, 
NDRC would provide a director who had had 
wide experience in fundamental research in the 
fields involved. It was proposed that the At- 
lantic coast laboratory be located at New Lon- 
don, Connecticut, and that the Pacific coast 
laboratory be located at San Diego, California. 
c See Appendix B. 


This proposal was submitted to NDRC and 
was approved at its meeting of April 18, 1941. 
On this same date, Dr. Bush submitted to Ad- 
miral Robinson a memorandum 11 embodying 
the proposal and suggested that if Admiral 
Robinson concurred, NDRC would proceed to 
organize the special committees or sections con- 
templated, and to put the plan in operation as 
promptly as possible. Admiral Robinson re- 
plied 0 stating that the suggested setup seemed 
satisfactory and that he would initiate the nec- 
essary Navy arrangements for carrying it out. 


Early Stages of Organization 

Following the receipt of Admiral Robinson’s 
letter, Dr. Bush f immediately asked Dr. Jewett 
to proceed to put the plan into effect. Dr. Tate, 
who was still in England, had been appointed 
vice-chairman of Division C, NDRC in Decem- 
ber 1940. He was now designated Chairman of 
Section C-4 which was to be concerned with 
submarine detection. 

Dr. Jewett, on April 23, 1941, called a con- 
ference with Doctors W. D. Coolidge, E. H. 
Colpitts, 0. E. Buckley, and C. O’D. Iselin to 
discuss the detailed organization of the sub- 
marine detection program. Subject to approval 
of the contracting universities, Mr. T. E. Shea, 
Vice-President of the Electrical Research Prod- 
ucts Company, was asked to assume the direc- 
torship of the New London laboratory and Dr. 
Vern 0. Knudsen, Dean of the Graduate Divi- 
sion, University of California at Los Angeles, 
was asked to assume the directorship of the 
San Diego laboratory. 

Proposed Contracts 

On April 29, 1941, Dr. Jewett called a con- 
ference with Messrs. Colpitts, Shea, and G. B. 
Pegram, Dean of the Graduate School, Colum- 
bia University, to discuss contractual arrange- 
ments which would be made to staff and oper- 
ate the east coast and west coast laboratories. 
Dean Pegram was asked if Columbia Univer- 
sity would become the contracting agent for the 

d See Appendix C for letter of transmittal. 

e See Appendix D. 

f See Appendix E for letter to NDRC. 


28 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


east coast laboratory, and Dr. Knudsen was 
asked to determine whether or not the Univer- 
sity of California would be the contracting 
agent for the west coast laboratory. 

On May 1, a conference was held at the Na- 
tional Academy of Sciences’ Building in Wash- 
ington, which was attended by Messrs. Jewett, 
Colpitts, Coolidge, Shea, Pegram, R. W. King, 
Iselin, and Knudsen. Representing the Navy at 
this meeting were Admiral Robinson and Lieu- 
tenant Commander M. K. Kirkpatrick, who 
were concerned with the providing of facilities 
at New London and San Diego by the Navy. 
Commander Kirkpatrick was appointed liaison 
officer to consult with Mr. Shea regarding the 
principal requirements of the proposed NDRC 
laboratory at New London. Dr. Knudsen was 
asked to consult with Captain W. J. Ruble, Di- 
rector of the U. S. Navy Radio and Sound Lab- 
oratory at Point Loma, San Diego. Because 
Dr. Tate had not yet returned from England, 
Dr. Jewett asked Dr. Colpitts and Dean Pegram 
to take preliminary steps in setting up an or- 
ganization. 

On May 19, 1941, Doctors Tate and Slichter 
returned from England, and on June 5, the fol- 
lowing Section C-4 members were officially ap- 
pointed: Carl D. Anderson, E. H. Colpitts, 
W. D. Coolidge, E. 0. Lawrence, Max Mason, 
and G. B. Pegram. 

As a first step in setting up a central head- 
quarters, space was rented on the 11th floor at 
172 Fulton Street, New York City. Dr. Elmer 
Hutchisson was appointed Technical Aide and 
was asked to set up the New York office. On 
July 1, Miss Fern Sullivan was appointed to the 
staff and began to organize secretarial facili- 
ties. 


nal Company in Boston to discuss possible proj- 
ects. 

On March 28, 1941, a conference was held at 
BTL at which a memorandum* prepared by Dr. 
Fletcher, entitled “An Outline of Fundamental 
Research Work on Underwater Acoustics,” was 
presented. 

Also discussed at this meeting was a memo- 
randum 11 prepared by Mr. W. H. Martin, en- 
titled “Suggested Program on Measurement 
Means and Technique for Underwater Work.” 

Magnetic Detection 

In addition to these discussions on under- 
water acoustics, Dr. Slichter had been giving 
considerable thought to the feasibility of de- 
tecting submarines by magnetic methods. 

For some time, the Gulf Research and De- 
velopment Corporation laboratories had been 
working to develop a magnetic method of locat- 
ing mineral deposits, and it seemed possible 
that some of the results of the Gulf research 
might be adapted to the detection of a magnetic 
mass under the sea as well as one under the 
earth. 

As early as November 20, 1940, Dr. Slichter 
had proposed to Dr. Jewett a scheme * 1 for mag- 
netic detection which he thought might have a 
range of hundreds of feet, possibly as much as 
2,000 feet. Dr. Slichter believed that the sweep- 
ing rate could be made to compare favorably 
with supersonic gear on surface craft in which 
the greater detection range was offset by the 
comparatively slow speed of a surface vessel. It 
was primarily to learn of the progress being 
made by the British in this field that Dr. Slich- 
ter went to England with Dr. Tate in April 
1941. 


8,1,4 Formulation of a Technical Program 

Considerably before the formal request for 
NDRC to undertake an investigation of the 
field of antisubmarine warfare, Dr. Tate and 
others had given much thought to a program of 
work which might be conducted if authoriza- 
tion were given. In March 1941, conferences 
were held at the Bell Telephone Laboratories 
[BTL] in New York and at the Submarine Sig- 


OCEANOGRAPHIC STUDIES 

Early thinking had taken other directions. 
In August 1940, C. O’D. Iselin, Director of 
the Woods Hole Oceanographic Institution 
[WHOI] sent to Dr. Jewett a memorandum 
concerning the research facilities applicable to 
submarine warfare available at WHOI. He in- 
dicated the possibility of studying the impor- 

S'See Appendix F. 

h See Appendix G. 

1 See Appendix H. 



EARLY ORGANIZATION AND GENERAL PROGRAM 


29 


tance of the thermal structure of the ocean as 
a factor in submarine detection methods. After 
considerable discussion with the Navy, a de- 
tailed outline j of the proposed study of the 
oceanographic aspects of the sound-ranging 
problem was prepared on September 19, 1940. 
There was outlined, in order to carry out the 
study, field work, laboratory work, and instru- 
mental developments which would be neces- 
sary. The Atlantis , the research vessel of 
WHOI, could be employed approximately half- 
time on this project, and could, in cooperation 
with a vessel such as the destroyer USS 
Semmes, obtain a great amount of information 
in this field. 

The program of work outlined by WHOI 
seemed so important that NDRC on September 
27, 1940, decided to set up a contract with this 
institution for an amount of $100,000 to carry 
on this program over a period of two years. It 
was recognized that this work was basic to any 
broader program which might be undertaken 
and that there was no reason for not beginning 
that work early. If and when a more compre- 
hensive antisubmarine program were started, 
the work being done at Woods Hole would fit 
into the general program. Dr. Tate, therefore, 
kept in close touch with this work. 

31 * 5 Central Laboratories 

As soon as it became evident that two cen- 
tral laboratories were to be organized, detailed 
programs for these laboratories were formu- 
lated. The immediate program contemplated 
for the New London laboratory involved (1) 
study of the possibilities of magnetic detection 
methods; (2) study of the possibilities of op- 
tical detection methods; (3) further develop- 
ment of supersonic detection methods and 
equipment; (4) study of types of sonic detec- 
tion equipment, other than supersonic; (5) in 
cooperation with WHOI, study of correlations 
between oceanographic conditions in the At- 
lantic with the performance of various types of 
detection equipment; (6) study of background 
noises and methods of reducing them; and (7) 
development of improved acoustical measur- 
ing equipment. 

j See Appendix I. 


The San Diego laboratory was assigned pri- 
mary responsibility for carrying out funda- 
mental investigations. At a meeting of an ad- 
visory group at Pasadena on June 7, 1941, it 
was agreed that immediate work should be be- 
gun on the following projects. 

1. Study of the reflections of impulse sounds 
from boundaries in typical areas of the ocean 
near San Diego, in which the sound conditions 
vary from exceptionally good to average and 
decidedly poor. 

2. Investigation of the sound transmission 
properties of typical ocean areas, using low-, 
medium-, and high-frequency sound in the 
audible range, and low, medium, and high fre- 
quencies in the supersonic range. 

3. Immediate work on the development of a 
“predictor,” or attack meter. 

As a result of this preliminary planning, a 
rather complete program in the field of anti- 
submarine warfare was prepared and pre- 
sented to NDRC at its meeting of June 12, 1941. 

The work of the central laboratories is de- 
scribed in detail in later sections of this chap- 
ter. 

In June 1941, a research and development 
program was established under contract at 
Harvard University. During its life, the pro- 
gram included the developments of important 
improvements to existing sonar gear and the 
development of one of the two principal types 
of scanning sonar, basic research on trans- 
ducers, and highly significant work in the de- 
velopment of acoustic torpedoes. In addition, 
valuable work was done to devise sonar test- 
ing and training equipment. Under the leader- 
ship of Director Frederick V. Hunt, of Cruft 
(formerly Associate Professor of Physics and 
Communications Engineering at Harvard), the 
Harvard Underwater Sound Laboratory, with 
the central laboratories at New London and San 
Diego, was one of the three principal labora- 
tories engaged in sonar research and develop- 
ment work. 

316 Initiation of Formal Section Meetings 

The first formal meeting of Section C-4 oc- 
curred in New York on June 11, 1941. Messrs. 
Tate, Colpitts, Coolidge, Iselin, King, Pegram, 


30 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


Shea, and Slichter were present. The principal 
items of business presented to the meeting were 
the technical programs at the New London and 
San Diego laboratories and the budget both for 
the fiscal year ending June 30, 1941, and the 
fiscal year ending June 30, 1942. The members 
of the section approved the programs and the 
following budget was set up. 


Estimate of Expenditures 



Through 
June 30, 
1941 

July 1, 1941- 
June 30, 
1942 

For the New London laboratory 

$ 45,000 

$1,000,000 

For the San Diego laboratory 
For the contract with industrial 

30,000 

900,000 

laboratories 

For university or other non- 

60,000 

800,000 

profit laboratories 

5,000 

300,000 

For administration 

2,000 

100,000 


$142,000 

$3,100,000 


Immediately after the meeting on June 11, 
1941, Dr. Tate submitted to Dr. Jewett the 
budget which had been approved at the section 
meeting. This was for presentation at the 
meeting of NDRC to be held the next day. At 
the meeting of NDRC, authorization was given 
to enter into the following contracts. 

For Operations Through June 30, 1941 

Columbia University for the operation of the 

New London laboratory $ 45,000 

University of California for the operation of 
the San Diego laboratory 30,000 

Harvard University for preliminary studies of 
submarine noises 5 qqq 

Western Electric Company for development of 
magnetic detection methods 5,000 

General Electric Company for development of 
magnetic detection methods 5,000 

For Operations for the Fiscal Year Beginning 
July 1, 1941 from 1941-42 Funds when Available 
Columbia University for initial operations of 
the New London laboratory $300,000 

University of California for initial operations 
of the San Diego laboratory 300,000 

Western Electric Company for study of hydro- 
phonic calibration and measurement 20,000 

Western Electric Company for development of 
standard projectors 15 qoo 

Western Electric Company for development of 

standard pickup units 15 qoo 


The scope of the division’s program ex- 
panded rapidly necessitating corresponding ex- 
pansions in facilities, staffs, and expenditures 


of the laboratories established to undertake 
work for the division. Also, the number of con- 
tracts with industrial organizations was in- 
creased. As some measure of the activity in- 
volved, the annual expenditures under the di- 
vision’s contracts quite promptly rose to, in 
round figures, $14,000,000. This, of course, 
takes no account of cost of ship facilities, ship 
personnel, and buildings furnished by the 
Navy, which was a very substantial item. 

In the following sections certain of the fa- 
cilities organized under Division 6 will be de- 
scribed. 

32 FACILITIES ORGANIZED UNDER 
DIVISION 6 

Central Headquarters 

In June 1941, a headquarters office was set 
up at 172 Fulton Street, New York. The staff 
of this office included Dr. Tate, then Vice- 
Chairman of Division C and Chairman of Sec- 
tion C-4, Dr. Colpitts, then Consultant to Divi- 
sion C, several technical aides, and a secre- 
tarial staff. As the work of the group expanded, 
more space was needed and in July 1943, the 
headquarters office moved to the Empire State 
Building, first on the 50th floor and later on 
the 64th floor. 

It was the responsibility of this administra- 
tive group to establish the general program of 
work and after examining and sifting out the 
various suggestions of specialists in the fields to 
be covered, to propose to Section C-4 contracts 
with academic and industrial institutions to 
carry out the work required. The section met 
several times a year to consider critically the 
proposals submitted and, if satisfactory, to 
recommend them for action by NDRC. Orig- 
inally, the section consisted of Dr. Tate as 
chairman and Doctors Anderson, Colpitts, 
Coolidge, Lawrence, Mason, and Pegram. In 
August 1941, Messrs. Paul D. Foote, Philip M. 
Morse, and T. E. Shea were added to the section. 

An important adjunct to the central adminis- 
trative office was a group of scientists, at first 
designated the Program Analysis Group but 
later the Special Studies Group, employed un- 


FACILITIES ORGANIZED UNDER DIVISION 6 


31 


der a contract with Columbia University. This 
group, which will be described later, carried on 
a continuous analysis of the program of the sec- 
tion as related to its fundamental objectives. 

To assist the Navy in keeping in touch with 
the progress of the work of the section, com- 
prehensive reviews were held from time to time 
which were attended by a large and representa- 
tive group of naval personnel. Rear Admiral 
Robinson had appointed Rear Admiral A. H. 
Van Keuren, Assistant Chief of the Bureau of 
Ships, as the chief liaison officer with the Navy 
and the first of these reviews was held in his 
office on September 5, 1941. 

On July 1, 1941, the Office of Scientific Re- 
search and Development had been established 
by Executive Order. Dr. Bush was made direc- 
tor, and NDRC as well as CMR (Committee on 
Medical Research) became advisory commit- 
tees to the director. In the reorganization, Sec- 
tions C-4a and C-4b were merged as Division 6 
of NDRC. Dr. Tate was made chief of the divi- 
sion and Dr. Colpitts became Chief of Section 
6.1, which was the only section in the division. 
The organization of the work under way re- 
mained unchanged. The section and division 
headquarters were the same and the functions 
of the headquarters group remained essentially 
the same. 

Following a period of growth and organiza- 
tion, work proceeded in the following divisional 
units : 

New London Laboratory, contractor, Columbia 
University 

Airborne Instruments Laboratory, contractor, 
Columbia University 

Special Studies Group, contractor, Columbia 
University 

Underwater Sound Reference Laboratory, con- 
tractor, Columbia University 
Operations Research Group, contractor, Colum- 
bia University 

Field Engineering Group, contractor, Columbia 
University 

San Diego Laboratory, contractor, University 
of California 

Underwater Sound Laboratory, contractor, 
Harvard University 

Hydrodynamic Laboratory, contractor, Cali- 
fornia Institute of Technology 


Torpedo Power Plant Laboratory, contractor, 

Massachusetts Institute of Technology 
Torpedo Fuel Laboratory, contractor, Massa- 
chusetts Institute of Technology 
In addition, already established facilities were 
employed under contract, such as those of 
WHOI and of many industrial organizations. 
Detailed descriptions of certain of these organi- 
zations will be given in later sections of this 
chapter. 

An important part of the work of the divi- 
sion staff was the editing and distribution of 
reports of work going on in the laboratories. In 
coordinating a program having such a wide 
subject matter diversification as well as such 
wide geographical distribution as that of Divi- 
sion 6, it was essential that accurate and up- 
to-date progress reports be distributed at regu- 
lar intervals to all of those working in this field 
in Division 6 laboratories and in Navy labora- 
tories. It was important that the reports reach 
those who were authorized to receive them and 
yet there were many parts of the program 
which were so secret that the distribution had 
to be very limited. During the later stages of 
the work, a bimonthly printed bulletin of some 
50 to 100 pages which covered progress in all 
of the research work that had a rather general 
interest and could be given a wide distribution 
was prepared by the division. As each indi- 
vidual project was finished a final report was 
prepared by the laboratory and, after approval 
by the division chief, was distributed to an au- 
thorized list. Finally Division 6 contracted with 
Columbia University to assemble, edit, and 
print a summary report of the work of Divi- 
sion 6, of which this chapter is a small section. 

The remaining sections of this chapter will 
describe the separate research and laboratory 
facilities organized under sponsorship of Divi- 
sion 6. Little will be said in this chapter about 
the technical programs since these are the sub- 
ject of the several volumes which make up this 
final report. 

Special Studies Group 

The Special Studies Group, first termed the 
Program Analysis Group, was set up during 
the summer of 1941 under a contract with 


32 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


Columbia University (OEMsr-20) to make 
studies and analyses of various problems asso- 
ciated with subsurface warfare under the di- 
rection of Section C-4 and later under Division 

6. The studies requested and undertaken may 
be roughly classified into three groups. 

1. Study of the physical factors underlying 
the work carried on at various laboratories op- 
erating under Section C-4. 

2. Theoretical studies of both an analytical 
and a statistical nature of certain basic prob- 
lems connected with the methods, the instru- 
ments, and the tactics of subsurface warfare. 

3. Design of a torpedo capable of being 
dropped from a high-speed plane. 

The group expanded considerably after its 
inception. At one time, there were two sub- 
groups, A and B, under the direction of Dr. 
Slichter and Dr. W. V. Houston, respectively. 
Dr. Slichter transferred to other work on 
December 31, 1942, and the two groups were 
combined. On August 31, 1943, the personnel 
of the group included the director, Dr. Hous- 
ton, a full-time staff of 12 scientists, 2 part- 
time scientists, a group of computers, and an 
office force of 5 secretaries. A section of the 
Special Studies Group which became known as 
the Sonar Analysis Group performed the im- 
portant function of analyzing the data on un- 
derwater sound transmission collected by 
Woods Hole and the San Diego laboratory. The 
results of their analyses of these data were 
furnished to the Navy in a form to enable that 
Service to employ its conclusions effectively. 
The work of the Sonar Analysis Group was car- 
ried on in close liaison with the Navy groups 
interested. 

The more important projects to which the 
Special Studies Group contributed, and on 
which reports were issued, are as follows. 

1. Tactics of A/S Attack. (Studies in coop- 
eration with Operations Research Group.) 

2. Ordnance Probability Studies. 

3. Mines and Torpedoes. 

4. A/S Rocket Projectile (Mousetrap). 

5. Transmission of Underwater Sound. 

6. Prediction of Maximum Sound Ranges. 

7. Underwater Explosion Studies. 

8. Study of the Nature and Properties of 
Wakes. 


In addition, various members of the group 
assisted in the following programs. 

9. Directional Radio Sono Buoy. 

10. Practice Echo-Ranging Targets. 

11. Small Boat Listening Equipment. 

12. Improvement of WEA-1 Echo-Ranging 
Gear. 

13. Project MERCHANT— Study of Sound 
Gear for Protection of Fast Merchant Ships. 

14. Oceanographic Program. 

Also, the group operating in conjunction 
with the NDRC Transition Office assisted the 
laboratories in preparing projects for small- 
scale or quantity production, analyzing pos- 
sible methods of cutting down the time between 
the completion of research and the actual in- 
troduction of the device to Service use. 

Finally, this group was frequently called on 
to analyze various new suggestions for attack- 
ing and destroying enemy submarines and for 
protecting our own submarines. 


Underwater Sound Reference 
Laboratories 

It was clearly recognized that it would be 
necessary to establish accurate primary and 
secondary reference standards. Without such 
standards it would be impossible to compare re- 
sults obtained in the east coast laboratories 
with those obtained in Great Britain or even 
on our west coast. Consequently, on July 1, 
1941, a contract was arranged with the West- 
ern Electric Company, authorizing the Bell 
Telephone Laboratories to develop standard in- 
struments and testing equipment and to study 
testing and calibrating methods for use in un- 
derwater sound measurements. They were also 
authorized to set up test stations in locations 
suitable for carrying on this work in close rela- 
tion to the general subsurface warfare pro- 
gram of the NDRC for the Armed Services, 
principally the Navy. Test stations were set up 
under this contract at Mountain Lakes, New 
Jersey, and at Orlando, Florida. 

On April 15, 1942, at a meeting called by 
Admiral J. A. Furer, Coordinator of Research 
and Development for the Navy, it was decided 


FACILITIES ORGANIZED UNDER DIVISION 6 


33 


that these laboratories, in view of their impor- 
tance to other groups working on underwater 
sound, should be operated by an independent 
organization not having a direct interest in the 
development or manufacture of any under- 
water sound devices. Accordingly, on the rec- 
ommendation of Division 6 the laboratories 
were transferred by OSRD to Columbia Uni- 
versity, Division of War Research, to be oper- 
ated under contract OEMsr-‘20 beginning May 
1, 1942. Dr. Robert S. Shankland, Professor of 
Physics, Case School of Applied Science was 


Morse, Massachusetts Institute of Technology; 
H. F. Olsen, Radio Corporation of America; 
and Lt. (j.g.) J. T. Burwell, Office of Coordi- 
nator of Research. 

Arrangements were also made with the Bell 
Telephone Laboratories for the transfer to the 
laboratory staff on a leave ()f absence basis of 
six people, who had been associated with the 
work: E. Dietze, F. H. Graham, E. Hartmann, 
R. J. Tillman, M. E. Quinn, G. D. Weldon. 

In addition to the skeleton staff obtained 
from the Bell Telephone Laboratories, a group 



Figure 1 . Testing piers at the Mountain Lakes Station. The booths housing terminal equipment and 
the overhead monorail systems are visible. 


appointed Director. At the same time Admiral 
Furer appointed a committee for the standardi- 
zation of hydrophones to help correlate the 
work of the laboratories, and to advise on units 
and reference standards to be used generally 
in underwater sound measurements. 

The first meeting of the committee was held 
on April 24, 1942. Dr. Shankland was elected 
chairman. The members were P. N. Arnold, 
representing the Naval Research Laboratory; 
A. H. Inglis, Bell Telephone Laboratory; J. M. 
Kendall, Naval Ordnance Laboratory; Frank 
Massa, Brush Development Company; P. M. 


of physicists, engineers, technicians, and an 
office force were engaged to make the neces- 
sary tests and calibrations at the two test sta- 
tions, to carry out the necessary design work of 
mechanical and electrical devices needed for 
the calibration and test programs, and to make 
analyses and theoretical studies of the data ob- 
tained to be submitted in the form of reports 
for distribution by the division. 

The original equipment which the Bell Tele- 
phone Laboratories turned over to Columbia 
University comprised at each of the two test 
stations a laboratory building, testing pier 


34 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


and handling equipment, electrical measuring 
equipment, and hydrophone and projector 
standards suitable for making tests and cali- 
brations in the frequency range of about 40 c 
to about 100 kc. The testing equipment was 
continuously improved and expanded so that 
facilities eventually were arranged for cali- 
brations over a frequency range from 2 c to 


cate set of electrical testing equipment were 
provided for Mountain Lakes under contract 
OEMsr-212 between OSRD and the Western 
Electric Company. 

Only work of direct value to the war effort 
was undertaken by USRL. Tests for commer- 
cial concerns were made only when they were 
developing apparatus for the Navy (or in rare 



«on^tLinstrT.ments 8h ' freqUenCy Ca ‘ ibrati ° n tank ’ showin S ™chanical equipment for holding and post 


214 me, and for permitting measurements at 
powers up to 1,500 watts, hydrostatic pressures 
up to 150 psi, and temperatures ranging from 
0 to 100 C. Among the steps in the improve- 
ment were the complete replacement in the fall 
of 1942 of the original testing equipment at 
Orlando with BTL equipment of improved de- 
sign, and the rebuilding of the testing pier at 
Orlando so that devices weighing up to 2 tons 
could be accommodated. In the spring of 1943, 
a second pier and what was essentially a dupli- 


instances for the Army) and all such tests were 
made either at the request of the Navy or with 
its approval. No charges were ever made for 
tests or calibrations carried out by USRL, 
since none of its work could be classed as “com- 
mercial” in the usual sense of this term. 

The data and log sheets taken at the test sta- 
tions were sent to the New York office of 
USRL where they were analyzed and final re- 
ports on the work were prepared. 

During the war period USRL made tests and 



FACILITIES ORGANIZED UNDER DIVISION 6 


35 


calibrations for more than 25 organizations 
that were developing and using underwater 
sound devices in the war effort. These included : 
the National Research Council of Canada; the 
British Admiralty Delegation at Washington; 
Naval Ordnance Laboratory; Naval Research 
Laboratory; U. S. Signal Corps Laboratory; 
Bureau of Ships, Navy Department; USS 


Corporation ; Astatic Corporation ; General 
Electric Company; Edward G. Budd Manufac- 
turing Company ; Aircraft Radio Laboratory, 
Wright Field; Radio Corporation of America; 
Submarine Signal Company; Bell Telephone 
Laboratories, Murray Hil}, N. J.; and the 
Brush Development Company. 

In order to complete the record of the divi- 



Figure 3. View of high-pressure tank, showing side viewing ports. 


Semmes ; David Taylor Model Basin; U. S. 
Naval Mine Warfare Test Station; California 
Institute of Technology; New London Labora- 
tory; University of California, Division of War 
Research ; Massachusetts Institute of Tech- 
nology, Underwater Sound Laboratory; Har- 
vard University, Underwater Sound Labora- 
tory; Columbia University, Division of War 
Research, Field Engineering Group; Woods 
Hole Oceanographic Institution; Freed Radio 


sion’s calibration activities it should be added 
that after the transfer of the two sound refer- 
ence laboratories, as above indicated, provision 
was made for continuing certain work at BTL. 
Under one contract assistance was rendered to 
USRL in further development and expansion 
of its test facilities, while under a second con- 
tract BTL produced a substantial number of 
standard instruments which were distributed 
to Navy and NDRC agencies. 


36 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


32 4 The New London Laboratory 
Laboratory Facilities and Equipment 

The original plan for Section C-4 of NDRC, 
as already stated, included the establishment of 
two principal laboratories, one on the east coast 
and one on the west coast. The most suitable lo- 


became known as the New London laboratory. 

By arrangement with the Navy, a building 
was provided on the Coast Guard Training Sta- 
tion Reservation, Fort Trumbull, New London, 
Connecticut. The building, with approximately 
6,500 sq ft of floor space, was partly occupied, 
although unfinished, on July 9, 1941. A substan- 



Figure 4. The Orlando test station as seen from the pier. Heavy equipment is loaded onto a mine car 
by means of the boom and chain hoist at the left. The rails on which the mine car runs are shown in the 
foreground. 


cation in the east appeared to be New London 
where it would be possible to keep in close 
touch with the ComSubLant and his staff, the 
U. S. Navy Submarine Base, and the Electric 
Boat Company, where submarines would be 
available for target ships without too much dif- 
ficulty. A contract was drawn up between the 
United States Government and Columbia Uni- 
versity to establish and staff a laboratory which 


tial addition to this building was made by the 
Navy from January to March 1942, and at the 
time of termination of Contract OEMsr-1128, 
the New London laboratory had been enlarged 
so that it occupied a total area of about 50,000 
sq ft divided into approximately 22 per cent 
office space, 52 per cent laboratory and shop 
space, and 26 per cent storage and warehouse 
space. In addition, a test station which provided 



FACILITIES ORGANIZED UNDER DIVISION 6 


37 


a natural test tank approximately 80 ft deep, 
had been set up at Booth's Quarry, 5 miles from 
Fort Trumbull. This was used principally in 
testing fast-sinking depth charges and related 
ordnance items. 

The Navy also provided a staff of officers and 
men, under Lieut. Commander J. B. Knight, 
Jr., and through them provided policing and 
security arrangements, and liaison assistance 
in securing local vessels and services. 


By October 1941, the program was suffi- 
ciently crystallized to warrant discussion in a 
general conference with the Navy. Such a con- 
ference was held on October 6, 1941. Although 
certain other NDRC topics were discussed at 
that meeting, the bulk of the discussion had to 
do with the work of the New London labora- 
tory. Detection of submarines by magnetic 
methods, measurement of submarine depths, 
improvement of standard supersonic equip- 



Figure 5. General view of the Orlando testing pier. 


Originally, the work of the New London 
laboratory was confined to the field of sub- 
marine detection. This meant that the work 
was largely in the field of acoustical detection, 
and to a minor extent in the field of magnetic 
detection from aircraft. Certain preliminary 
work was done on optical detection methods, 
but this work was subsequently dropped. 

Because of the complexity of the problems 
related to the field of antisubmarine warfare, 
particularly submarine detection, it was neces- 
sary for the small staff to spend the initial 
months of work during the summer of 1941 in 
making a general analysis of the problems, es- 
timating the possibilities of profitable work 
along particular lines, and doing preliminary 
experimental and theoretical work to explore 
these possibilities. 


ment, antisubmarine ordnance methods, and 
radio sono buoys were discussed in detail. Work 
on improving the speed of descent of depth 
charges was described. 

The desirability of emphasizing, as rapidly 
as research would permit, the most important 
of the various projects was recognized, and as 
work continued through the fall months, efforts 
were made in this direction. By December 10, 
1941, sufficient additional progress had been 
made to warrant a second general meeting at 
New London. Rapidly descending standard 
depth charges, streamlined smaller depth 
charges with contact and magnetic fuzes, mag- 
netic detection from aircraft, attack-course 
plotters, depth-measuring apparatus, and mod- 
ifications of standard echo-ranging equipment 
were featured at this meeting. A new and rea- 


38 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


sonably accurate method of measuring depths 
of submarines was described in detail. The 
complete program also included certain sup- 
plementary problems on which the New London 
laboratory was working, including direct listen- 
ing equipment for surface vessels, listening 
equipment for our own submarines, and cali- 
bration methods. 


were cleared for action by the elimination of 
many programs and many lines of effort which, 
although promising from the long-range view- 
point, could not be regarded as likely to cul- 
minate in essential equipments on a foreseeable 
date. Instead, a group of high-priority prob- 
lems was selected which was within the scope 
of existing personnel and facilities for solution 



•< 


Figure 6. Air view of the CUDWR Underwater Sound Laboratory at Fort Trumbull, New London, 


The coming of war in December 1941, laid 
stress on (1) those projects which promised 
practical apparatus in the shortest time, and 
(2) those projects which were most closely re- 
lated to the tactical situations presented to the 
country after its entry into the war. 

Although the element of time was always 
foremost, the objectives of the laboratory 
changed frequently as experience was accumu- 
lated. After the initial exploratory period, decks 


in time to be of operational service to the Navy. 
This policy never was relaxed, and from it were 
developed managerial and technical methods 
which should be of interest to any similar fu- 
ture organization. 

Test Vessel Fleet. The test vessel fleet was 
maintained and operated entirely by the U. S. 
Navy, under the Commanding Officer, U. S. 
Navy Underwater Sound Laboratory. Navy 
personnel included a complement of 36 officers 



FACILITIES ORGANIZED UNDER DIVISION 6 


39 


ind 263 men, of whom approximately 21 offi- 
cers and 195 enlisted men were ships’ crews. 

Surface vessels, submarines, and aircraft 
"urnished by activities other than the New 
^ondon laboratory for specific sea trials or ex- 
;ended test programs were not, of course, part 
>f the permanent laboratory facilities, but per- 
laps should be discussed under this section in 
he interest of uniform subject treatment. Air- 
craft were frequently required in connection 
vith sono buoy tests and were obtained on 
hort notice, usually from the Naval Air Sta- 
ion at Quonset, R. I. Surface vessels in this 
ategory were used principally as submarine 
scorts for tests or exercises conducted in areas 
•utside of Block Island Sound and were nor- 
nally scheduled by the submarine base. 

In one instance, a submarine was assigned 
xclusively to the laboratory for a long-time 
est program. This was the USS S48 (SS159), 
n which the first triangulation-listening-rang- 


Table 1 . Test vessels assigned to the U. S. Navy 
Underwater Sound Laboratory. 


Classi- 

fication 

Name 

Length 

(ft) 

Displace- 

ment 

tonnage 

PY31 

Cythera 

205 

700 

PYc26 

Cymophane 

161 

450 

PYcl2 

Sardonyx 

175 

470 

1X54 

Galaxy 

131 

360 

1X87 

Saluda 

88 


1X97 

Martha's Vineyard 

138 

141 

SC665 


111 

110 

YP252 

(ex Wild Duck) 

104 

73 

YP253 

(ex Montauk) 

127 

137 

YP256 

(ex Phantom) 

70 

29 

CGR1985 

(ex Lady Luck) 

48 

15 

CGR3080 

(ex Valor) 

112 


C-2068 

( Flying Cloud) 

50 

15 

222093 

( Billie B) 

35 

7 

11818 

Motor boat 

35 

6V 2 

17625 

Motor launch 

30 

4 

17627 

Motor launch 

30 

4 

C-36109 

Plane personnel boat 

24 

2 Vs 

6593 

Motor boat 

21 


766 

Motor boat 

18 




Figure 7. Pier at New London laboratory showing part of the Navy facilities. 


ig system was installed. Semi-exclusive use of 
nother submarine, the USS Mackerel (SS204) 
as arranged over an extended period in con- 
ection with the development of sonar improve- 
lents culminating in the JT sonar system. The 
SS Mackerel was primarily assigned to the 


training of submarine personnel, but arranged 
its operations so as to be available for simul- 
taneous JT sonar system work on a regular 
basis. 

In cooperation with the ComSubLant, the 
laboratory instituted and administered a care- 



40 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


fully formulated plan for requesting the serv- 
ices of submarines for one-day or short-time 
sea trials. 

The importance of completely adequate lab- 
oratory facilities for the efficient prosecution 
of engineering developments was recognized by 
the management as fundamental. The procure- 
ment of machine tools, electronic equipment, 
and materials in a period of war shortages re- 


machine shop, an electronic shop, and stock 
rooms were so designed and operated as to per- 
mit maximum flexibility in meeting the needs 
of individual engineers and in fulfilling, with 
the ever-needed dispatch, the demands of group 
projects. The laboratory equipment included all 
reference standards necessary to the studies of 
acoustic phenomena in both air and water. 

Individual project or group laboratories were 



Figure 8. Interior view of the calibrating barge showing open sea well. 


quired unremitting effort by the laboratory 
purchasing group and frequent supplementary 
assistance from the Washington offices of 
OSRD, in order that the supply of working 
tools might be kept at a level commensurate 
with the needs of the staff. 

Group Laboratories. The general plan for 
the provision of laboratory facilities and sup- 
porting activities followed that favored by most 
industrial laboratory managements. Individual 
laboratories were provided for scientific 
groups assigned to specific phases of the devel- 
opment programs or kinds of work. A common 


provided and, in addition, a development shop 
which contained essential machine tools and 
other adjuncts of a well-equipped shop was 
available for use directly by the engineers in 
preliminary model building. 

Barge Facilities. “Floating” laboratory fa- 
cilities for carrying out equipment tests and 
measurements in sea water were provided by 
the calibrating barge (described in the discus- 
sion of “Electronic Design and Measurements” 
in this chapter) and by the Amada, a converted 
houseboat. The barge was permanently moored 
at the laboratory piers. The Amada was used at 



FACILITIES ORGANIZED UNDER DIVISION 6 


41 


sea for carrying out the type of work conducted 
on the barge. 

Shops and Drafting Room. The central elec- 
tronics shop occupied 1,800 sq ft and was 
staffed by skilled technicians under the direc- 
tion of a foreman. 

The machine shop, similarly, was staffed by 
skilled machinists under a foreman’s supervi- 
sion and occupied 6,500 sq ft, including the 
welding and sheet metal shop. A stockroom for 
raw materials and a tool room were included. 

A drafting room containing 21 tables under 
the supervision of a chief draftsman handled a 
substantial part of the design work as familiar- 
ity with both the equipment and the problems 
of its design increased, thus relieving the engi- 
neers of a large part of their detailed design 
work load. Electronic drafting was also handled 
under the supervision of the chief draftsman. 

A photographic shop provided facilities for 
making and maintaining a complete photo- 
graphic record of every phase of the labora- 
tory’s activities. Blueprint and photostat shops 
supplemented the work of the drafting depart- 
ment and other services. 

Recording Laboratory. The Recording Labo- 
ratory should be regarded, perhaps, as having a 
development or engineering function in its own 
right, but nevertheless, it was an indispensable 
adjunct to the other development groups. At its 
maximum strength, this group included six 
men in addition to the supervisor. 

Staff Organization 

The contract stipulated in part that, “The 
Contractor shall . . . staff . . . (the) laboratories 
and other necessary facilities and services. . . .” 
Here again, as in the case of the acquisition 
of laboratory equipment and machinery, the 
management found itself in competition with 
the accelerating demands of industrial and non- 
industrial research and development organiza- 
tions during a period of unprecedented war- 
time expansion. In addition, it was the policy of 
the Office of Scientific Research and Develop- 
ment to offer salaries which, though represent- 
ing no financial loss to prospective employees, 
would not in themselves constitute a monetary 
inducement to join the laboratory. It was be- 
lieved, and the belief has been shown sound, 


that the effective fulfillment of the broad policy 
of discharging responsibilities with the utmost 
dispatch rested ultimately on the extent to 
which each individual was willing to forget 
self-interest and to accept as his reward the 
satisfaction of a task well done. 

The mechanics of recruiting personnel were 
influenced by the same sense of urgency and 
need as that influencing the acquisition of 
property and facilities. In the early days of the 
laboratory, the scientific nucleus was recruited 
from among the engineering acquaintances and 
professional colleagues of the laboratory super- 
visors. It soon became apparent that other and 
wider sources of supply were needed. A per- 
sonnel representative traveled widely in search 
of additional staff members. Colleges, schools, 
and industrial organizations were combed for 
needed talent and proved to be valuable sources. 

The field interview method of recruiting was 
employed through the early part of 1942, but 
after July of that year most of the additions 
to the staff, while selectively interviewed in the 
field, were not employed until they had visited 
New London for further discussions and had 
been evaluated for assignment to specific proj- 
ects. This procedure became especially desirable 
as the later staff additions were mostly made to 
fill definite “spot” openings in a generally bal- 
anced organization. 

The nonscientific staff included the personnel 
employed in the various mechanical and elec- 
trical shops, the drafting room, clerical, steno- 
graphic, and maintenance forces, and the sev- 
eral service groups which will be discussed in 
greater detail at a later poinj:. For the most 
part, nonscientific personnel were recruited in 
the New London area, although the search for 
people with specific qualifications, particularly 
in the skilled grades, occasionally made neces- 
sary a more extended search. Until the autumn 
of 1942, the laboratory personnel was 100 per 
cent male because of Naval Reservation restric- 
tions. At that time inability to retain the 
younger men of the nonscientific staff in the 
face of Selective Service demands made it nec- 
essary to employ women for work for which 
they were qualified. 

The fluctuating draft deferment policy under 
which the Government was obliged to operate 


42 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


plagued this laboratory throughout its exist- 
ence. Important technical employees, especially 
among the younger men, were constantly faced 
with uncertain draft status, and their efficiency 
was frequently impaired. It cannot be too 
strongly stated that a clear and uniform draft 
policy is essential for the effective operation of 
Government-sponsored research groups. 

Distribution of Personnel . Although it is 
recognized that the particular personnel prob- 
lems, the scope of the work, and the relative 
needs for a scientific and nonscientific staff 
were somewhat unique at New London, it might 
be helpful to the formulation of personnel poli- 
cies of future laboratories to set down the dis- 
tribution of the total laboratory staff among 
the various employment classifications. 

Table 2 shows the distribution of the total 
personnel on August 30, 1943, when Contract 
OEMsr-20 was terminated, and on January 1, 
1945, shortly before the management was as- 
sumed by the Naval Research Laboratory. In 
studying the table it must be borne in mind 
that the group shown includes only the civilian 
staff employed by Columbia University and 
does not include the naval complement respon- 
sible for the maintenance and operation of the 
physical plant and the fleet of test vessels. 

Table 2. Growth of personnel. 


August January 1, 

Employment 1943 1945 

classification (OEMsr-20) (OEMsr-1128) 


Scientific staff 

Nonscientific staff 

94 

116 

Mechanical shops 

29 

43 

Electronic shop 

21 

34 

Drafting department 

16 

24 

Accounting and financial 
Building maintenance 

6 

7 

and general service 
Purchasing and ware- 

36 

38 

housing 

13 

11 

Marine facilities 

4 

3 

Dining room 

9 

11 

Photographic 
Stenographic and 

8 

7 

general clerical 

29 

34 





265 

328 


Apparatus Development Groups. Basically, 
the apparatus development work was concen- 
trated in individual groups under a number of 


development supervisors who had had exten- 
sive experience in industry. Each group en- 
compassed the work on a number of more or 
less related problems and the development su- 
pervisor was assisted by project leaders who 
were individually responsible for a single proj- 
ect. During the spring and summer of 1943 the 
work was concentrated in the antisubmarine 
warfare field. Four principal development 
groups were in operation, including in their 
schedules the completion of work already begun 
in 1942, and the development of new devices 



Figure 9. The YNG22 barge used for training 
naval sonar personnel. 


for which requirements had been established 
subsequently. These principal fields of endeavor 
were: ordnance, listening detection devices, 
echo-ranging detection devices, and underwater 
acoustic devices. 

An attempt was made to assign to each 
project a group of men whose individual skills 
were consistent with the technical require- 
ments. By this time it was possible to recruit 
men on the basis of specific types of needed 
experience. Intensive recruiting was continued 
throughout the spring of 1943. The assignment 
of engineers on the various projects was changed 
from time to time as requirements dictated but, 
generally speaking, men assigned to apparatus 
development work continued in this field 
throughout the remainder of their employment 
with the New London laboratory. 

Keeping in mind the fact that the New Lon- 
don laboratory was intended to concentrate on 
the provision of equipment to the operating 


FACILITIES ORGANIZED UNDER DIVISION 6 


43 


forces, by the summer of 1943 it appeared that 
further development on new devices in the anti- 
submarine warfare field would not, by and 
large, result in the provision of equipment to 
the Services until sometime late in 1944. Pro- 
duction had begun on most of the devices then 
under development and, except for “spot” jobs, 
the need for long-term investigations along 
new lines was not immediately apparent. About 
this time, as a result of close association with 
the submarine force at New London, it was 
believed desirable to explore the needs of our 
own submarines in future Pacific operations. 
Following a visit to Pearl Harbor in August 
1943, the management, with the assistance of 
the Navy and under the guidance of Division 6, 
organized a program of development work for 
the submarine forces. A number of additional 
development groups were organized and those 
groups then in operation embarked on the new 
program as their work in the antisubmarine 
field diminished. 

Technical Service. Early in 1943 it was rec- 
ognized that the apparatus development groups 
could not be individually staffed with all of 
the specialists required. Consequently it proved 
expedient to set up and maintain a technical 
service and consulting department which could 
supply special measuring or design service on 
short notice and for as long a time as was 
necessary to the individual project groups. The 
head of this staff department reported to the 
director of the laboratory and ultimately be- 
came an assistant director of the laboratory. 
It is probable that comparable laboratory op- 
erations would find value in such a centraliza- 
tion of technical staff resources. The particular 
technical service functions at New London 
were administered by five group leaders and 
included the following: sound recording; hy- 
drophone production development, including 
acoustical calibration; acoustical studies, in- 
cluding measurements and listening tests at 
sea ; electronic design and measurements ; data 
analysis and computations, including oceano- 
graphic studies. About 30 members of the sci- 
entific staff were employed in this work. Al- 
though it was not the policy to insist that all 
work of the above nature be done by these 
groups, in practice most of it was turned over 


to them because of their special knowledge and 
facilities. 

Sound Recording. Sound recording activities 
of the New London laboratory were of excep- 
tional value in the development of training 
programs. During the past few years, the use 
of “direct recording” which eliminates the need 
for record processing except in cases where 
many copies are required, has greatly extended 
the value of records as a technical aid. Full 
advantage was taken of the latest techniques. 
Initially, the principal use of sound recording 
was to demonstrate, in the laboratory, under- 
water sound conditions at any given time dur- 
ing a test at sea and to illustrate typical forms 
of water noise and ship signals. Later it be- 
came apparent that sound recording techniques 
had numerous applications not originally fore- 
seen and a recording group was formally estab- 
lished. It then became the general practice to 
use the recordings to preserve the acoustic 
phenomena of field tests or to transfer them 
to the laboratory for more detailed study and 
analysis. For instance, in the case of changing 
sounds, such as torpedo noise which varies 
rapidly because of the speed of the torpedo, 
the only way to make an analysis is to record 
the sound and then repeat it many times 
through an analyzer. In other cases, machinery 
sounds of submarines have frequently been re- 
corded in a few minutes or seconds and then 
analyzed at length in the laboratory, thus mini- 
mizing the demands on submarine operating 
time. 

A direct result of these activities was the 
collection of an extensive group of recordings 
of underwater acoustic phenomena, selections 
from which could be used to give listeners, at 
one sitting, a comprehensive audition of any 
phase of underwater sound. Steps were taken 
to segregate the recorded material into divi- 
sions dealing with specific subjects in a record 
library and a record catalog was then issued. 
This catalog, kept current by means of periodic 
supplements, contained over 2,000 records at 
the close of the contract. 

Increasing use was made of recordings for 
personnel training, both for listening and echo 
ranging. Special trainer equipments were de- 
veloped using the phonograph records as a 


44 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


principal element. Among these were the model 
QFL and QFM trainers, for teaching operation 
of the tactical sound range recorder and tor- 
pedo detection, respectively, and the radio sono 
buoy trainer. Several thousand complete sets 
of several training record series were distrib- 
uted by the laboratory and the Navy to the 
forces afloat throughout the world and to naval 
training activities and other laboratories. 


of film in many instances, principally because 
of the distance from satisfactory film process- 
ing facilities and the time and care required 
for high quality processing. However, magnetic 
wire and film-embossing recording facilities 
were used extensively where their character- 
istics were suitable. 

In almost all cases it was found that changes 
and improvements were required to fit com- 



Figure 10. Sonar training class studying the operation of the sound range recorder. 


Disk recording was employed for most pur- 
poses because of its many advantages and the 
wide distribution of disk reproducing equipment. 
The frequency and volume characteristics of 
the equipment were adequate for full-quality 
recording of all acoustic phenomena under in- 
vestigation, and in no case was the usefulness 
of a record impaired or the making of a record 
of completely satisfactory quality rendered im- 
possible by deficiencies in the response of the 
equipment. No photographic film sound record- 
ing was attempted, in spite of the advantages 


mercial apparatus to the needs of the labora- 
tory. Consequently, the work of the Sound Re- 
cording Department involved the design and 
construction of much recording equipment and 
the modification for laboratory use of several 
types of recorders and recording mediums. As 
a result, a great deal of consulting work was 
done on recording problems and test informa- 
tion has been furnished to the Navy and to 
other interested groups on the performance of 
a variety of magnetic, engraved-disk and em- 
bossed-film recorder-reproducer equipments. 



FACILITIES ORGANIZED UNDER DIVISION 6 


45 


Electronic Design and Measurements. Be- 
cause sonar equipment invariably involves a 
great deal of electronic apparatus, often of 
great complexity, electronic design occupied a 
large portion of the time of the New London 
laboratory. It was found convenient to set up 
a group which would be available to do elec- 
tronic design or measurements work for the 
development supervisors. Thus, the electronic 
work was done by engineers specializing in 
these techniques and the time of engineers ca- 
pable in field work was conserved and could 
be applied to the field testing of the equipment. 
No pressure was put on the staff to use these 
services if they preferred to do their own elec- 
tronic design work, but it was found that the 
seven engineers comprising the group were 
heavily loaded at all times. The type of work 
done by them is shown in the following list of 
representative projects: 

1. Special impedance bridges, detectors, 
measuring amplifiers, and field test sets. 

2. Test specifications for amplifiers and other 
electronic equipment. 

3. Equipment design, including the NL-105, 
NL-117A and NL-118A listening amplifiers, 
single sideband underwater-telephony trans- 
mitters, a submarine echo-ranging signal gen- 
erator, the OAY sound measuring equipment, 
and the depth charge range estimator proto- 
type model. 

4. Design of special transformers and filter 
networks to meet specific needs. 

5. Radio transmitter and receiver problems 
in connection with the expendable radio sono 
buoy and the directional radio sono buoy. 

Hydrophone Development and . Calibration. 
The Hydrophone Production Development 
Group stood ready to provide a commercially 
practicable design of hydrophone for any proj- 
ect undertaken by the laboratory. The problem 
would be reviewed and if a crystal device were 
decided upon, an outside laboratory or manu- 
facturer would be engaged to produce the de- 
sign. For most of the projects at New London, 
magnetostriction hydrophones seemed to pos- 
sess the qualities most desired. These hydro- 
phones were developed by the New London 
laboratory. Problems involved were the heat 
treatment of nickel, and measuring techniques 


to control the heat-treating process; plastic- 
casting techniques in vacuum; new cements 
and waterproofing compounds ; and methods of 
winding and magnetically polarizing the hy- 
drophones. Entirely new methods of fabrica- 
tion were devised and the techniques were 
taught to manufacturers. 

Since acoustic calibrations were required at 
every step in this work, this group also oper- 
ated the calibrating barge moored at the lab- 
oratory pier. This barge was equipped to make 
rapid calibrations of all types of hydrophones 
and new calibration methods were developed 
as the requirements of the hydrophone pro- 
gram made them necessary. The barge was also 
available for calibration of all acoustic devices 
used by the laboratory, whether developed by 
the Hydrophone Production Design Group or 
not. Close liaison was maintained with USRL 
at Mountain Lakes, New Jersey, and the stand- 
ard hydrophones used on the barge were peri- 
odically returned to them for calibration. The 
barge was located only a few hundred feet 
away from the laboratory, and a sufficient staff 
was maintained so that high priority jobs could 
usually be done on the day when the service 
was requested. This speeded up the develop- 
ment work significantly. The extensive comple- 
ment of equipment on the barge was fully 
justified, since effective development depends to 
an important degree on accurate measurements 
furnished when needed. 

This group, together with the Transducer 
Research Group, developed a set of rigorous 
tests for magnetostriction hydrophones, for 
which the necessary test equipment was pro- 
cured. The NL-124 and NL-130 hydrophones 
are examples of instruments capable of passing 
these tests and exemplify the work of the group. 
Compared to the original JP-1 hydrophone, the 
NL-124 is 17 db (sevenfold) more efficient, is 
split and sectionalized for right-left indication 
and delobing, is permanently magnetized, is 
not subject to corrosion or denting, has a sep- 
arable cable connector, withstands hydrostatic 
pressure of 500 psi, and is undamaged by the 
shock wave produced by the explosion of 25 lb 
of TNT at a distance of 15 ft. 

Data Analysis and Computations — Oceano- 
graphic Service. This group was established at 


46 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


about the halfway mark in the laboratory’s 
existence and was an immediate success. It op- 
erated under the direction of an engineer who 
had been generally active in both the acoustical 
measurements and development groups of the 
laboratory. His experience enabled him not only 
to grasp quickly the analysis and computation 
problems of others, but also to suggest ways 
of field testing or recording data in such a 
manner as to simplify the analysis work. The 
group carried out for the project groups a great 
many of the time-consuming calculations, curve 
plots, and graphical analyses that are a neces- 
sary part of any scientific program. In a few 
instances, members of the Data Analysis Group 
participated in actual analysis of phonograph 
recordings of submarine auxiliary noises, and 
participated in enough field tests to keep them 
acquainted with the changing requirements for 
data analysis. 

The Oceanographic Service functions were 
established within this group because they con- 
sisted so largely of analysis and computations 
based on data gathered at sea by the two mem- 
bers of the scientific staff assigned to this work, 
and by members of ships’ crews trained and 
supervised by them. Many times the oceano- 
graphic studies were able to explain seeming 
anomalies in important test results and thus 
clarify and make usable certain data that would 
otherwise have been merely confusing. Their 
work demonstrated the fact that no laboratory 
doing underwater sound experimentation can 
afford to be without the services of oceanog- 
raphers. 

Acoustic Measurements and, Listening Tests 
at Sea . This group operated Columbia Univer- 
sity’s test vessel Amada and carried out a large 
number of specific project investigations as 
well as a general program of fundamental 
listening studies, the latter on an “as time 
permits” basis. All members were experienced 
in the techniques of field measurements em- 
ploying electronic and acoustic apparatus, and 
frequently were loaned to project development 
groups for varying periods to conduct special 
tests involving their type of knowledge. An ex- 
ample of this was an investigation of the 
effectiveness of rubber isolation mounting for 
the JP-1 hydrophone, which occupied the time 


of one man in the submarine listening equip- 
ment program for several months. Examples 
of the problems investigated by the group as a 
service to others are the following. 

1. Investigation of the probable aircraft de- 
tection range of listening devices on a subma- 
rine. 

2. Selection of the best hydrophone for the 
directional radio sono buoy. 

3. Use of the Amada as an artificial sound 
target for many listening tests and particularly 
for interference tests during the triangulation- 
listening-ranging development. 

4. Measurement of background noise and the 
sound output of vessels and submarines under 
various specified conditions. 

5. Construction and installation of artificial 
sound-source equipment on a target boat for 
training purposes. 

Pearl Harbor Division 

By July of 1944 the prosubmarine program 
of the laboratory had reached a point where a 
number of developments were in the produc- 
tion stage. These items were sufficient in num- 
ber and variety to cause concern over the prob- 
able load to be thrown on the submarine forces 
installation and training activities, especially 
since in only one or two instances were the 
manufacturers in a position to provide field 
supervision of installation of the gear. The 
management, under the guidance of the Chief 
of Division 6, NDRC, proposed the establish- 
ment of an engineering group at Pearl Harbor 
(1) to serve as an outpost of the laboratory in 
the introduction into use of new equipment de- 
signed at New London, (2) to assist the staff 
of ComSubsPac in the evaluation of suggestions 
from the operating forces, (3) to assist in the 
appraisal at Pearl Harbor of new devices under 
operating area conditions, and (4) to assist the 
ComSubTrainPac at that activity in the expan- 
sion of selection and training programs. 

Although these initial plans contemplated a 
group of 25 men, including engineers, tech- 
nicians, and office assistants, and the establish- 
ment of a small shop or testing laboratory, 
problems attendant on the housing and main- 
tenance of such a large staff caused a reduction 
in the number such that at maximum strength. 




FACILITIES ORGANIZED UNDER DIVISION 6 


47 


12 men including 3 training specialists were 
stationed at Pearl Harbor. 

The importance and value of the Pearl Har- 
bor division of the New London laboratory 
cannot be minimized. During the 8 months of 
its existence, a total of some 800 letters flowed 
between the director of the New London labora- 
tory and the supervisor of the Pearl Harbor 
Group. Most of these letters dealt with engi- 
neering and development matters and this il- 
lustrates the value of close liaison between the 
development laboratory and the forces afloat. 
Experience in the operation of this group leads 
to the conclusion that by the provision of means 
for rapid interchange of information between 
forces afloat and development groups, much 
time can be saved and the resulting devices can 
be caused to meet more adequately the require- 
ments of the Services. 

Termination Policies 

The problems attendant on the termination 
of the contract with respect to the handling of 
personnel matters occupied the time of the 
management importantly throughout the latter 
half of 1944. Having expended a great deal of 
energy and thought on the proper treatment 
of staff members at the time of their employ- 
ment and throughout their stay in New London, 
it followed logically that a conscientious effort 
should be made to terminate the employment 
of these men in a manner which would reflect 
credit on OSRD, NDRC, and Columbia Univer- 
sity. It was thought that the attitude of these 
men as they left New London might influence, 
to some extent, the general attitude of the 
nation toward the conduct of research and de- 
velopment work in the postwar period and 
would make less difficult the recruiting of lab- 
oratory personnel should a need arise for their 
services at some time in the future. 

The Navy’s decision to continue operations 
at New London under the supervision of the 
Naval Research Laboratory and to assume re- 
sponsibility for the operation of the laboratory 
on March 1, 1945, simplified these problems to 
a considerable extent. Almost one-third of the 
members of the scientific staff accepted em- 
ployment with the Naval Research Laboratory 
and continued at New London. An equivalent 


number of men were transferred to the staff 
of the Radiation Laboratory at Cambridge, and 
the majority of the balance of the staff took 
employment with other research agencies en- 
gaged in war work. Every effort was made to 
place the men to the best advantage of the war 
effort and with a view to satisfying the em- 
ployees’ personal desires with the result that 
satisfactory employment was found for every 
member of the staff. 


The San Diego Laboratory 
General Organization 

The arrangements for the establishment of 
the San Diego laboratory were completed dur- 
ing the late spring of 1941 and were authorized 
in correspondence among NDRC, OSRD, and 
the University of California. Dr. V. 0. Knud- 
sen, Dean of the Graduate School of the Uni- 
versity of California at Los Angeles, was ap- 
pointed as director. It may be noted that at 
first this laboratory was known as the “San 
Diego Laboratory, University of California 
Division of National Defense Research,” and 
later after the United States entered the war, 
as the “San Diego Laboratory, University 
of California Division of War Research” 
[UCDWR]. More commonly, however, it has 
been referred to as the San Diego laboratory. 

The terms of the OSRD contract with the 
University of California provided that the con- 
tractor would equip, staff, and operate a lab- 
oratory for studies and experimental investi- 
gations in connection with and for the develop- 
ment of equipment and methods involved in 
submarine warfare. Further provisions author- 
ized the conduct of tests, the acquisition and 
equipping of vessels, and all other activities 
deemed requisite for the successful conduct of 
the program envisaged. 

The initial nucleus of personnel under the 
direction of Dr. Knudsen was housed for the 
first few months in the same building as 
the U. S. Navy Radio and Sound Laboratory, 
then under the direction of Captain W. J. Ruble, 
USN. The group of scientists and their as- 
sistants grew slowly by recruiting from the 
staffs of universities, colleges, industrial lab- 


48 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


oratories, and technical groups. These men had 
little or no indoctrination or training in the 
specific problems which they were to undertake 
or in the conduct of operations jointly with 
naval activities. In consequence, much of the 



Figure 11. Aerial view of the U.S. Navy Radio 
and Sound Laboratory on Point Loma, San Diego, 
California. 

early period was spent in acquiring some back- 
ground of knowledge essential for the intelli- 
gent and efficient approach to the various prob- 
lems with which they were confronted. 

As the staff grew and the scientific program 
took form, the need for proper procedures be- 
came apparent in order that the various duties 
and responsibilities of civilian and naval per- 
sonnel should be understood and discharged. 
As laboratory personnel acquired competence 
in this novel field and merited confidence in 
their efforts, the difficulties initially encoun- 
tered were considerably ameliorated. With the 
passage of months and successive changes in 
laboratory organization and cooperating naval 
commands in the area, a cordial relationship of 
mutual understanding and assistance became 
established. It is evident in retrospect that the 
effectiveness of the scientific group increased 
in direct proportion to the improvement in local 
liaison and the establishment of intimate work- 
ing relations with the U. S. Navy Radio and 
Sound Laboratory, the U. S. Fleet Sonar School, 
the local Submarine Squadron, and other naval 
commands. 

In accordance with the terms of the contract, 
the University of California undertook to con- 
duct such studies and experimental investiga- 


tions as might be requested from time to time 
by the contracting officer of the OSRD or his 
authorized representative. Members of this di- 
vision and section constituted an advisory com- 
mittee for the subsurface warfare program of 
which this laboratory was an integral part. 
Representation of the laboratory through its 
director, Dr. G. P. Harnwell, who succeeded 
Dr. Knudsen on April 1, 1942, and who was a 
member of Division 6, provided the point of 
view of the laboratory scientists in the broad 
planning and allocation of the work and insured 
an appreciation by the laboratory of its role 
in the program as a whole. Frequent confer- 
ences between the division and representatives 
of its contractors contributed immeasurably to 
liaison between the various groups engaged in 
studies and experimental work and fostered 
intimate collaboration between groups which 
were geographically widely separated. 

Liaison with the Navy. The first was a cen- 
tral liaison between the Navy and OSRD 
through the Office of the Coordinator of Re- 
search and Development for the Navy. Prob- 
lems which arose in operating units of the 
Navy were referred to appropriate naval bu- 
reaus, and these in turn submitted recommen- 
dations to the Office of the Coordinator in those 
instances where it appeared appropriate to en- 
list OSRD assistance. Proposals made by the 
Coordinator to the Director of OSRD were 
then considered and assigned to the appropriate 
subdivision of the civilian agency. If they lay 
in the field of subsurface warfare, cognizance 
was generally assumed by Division 6 and the 
projects authorized in the laboratory of one 
of the division’s contractors. In many instances, 
initiative was assumed by a contractor or an 
NDRC division, and comments and cooperation 
were invited from the appropriate naval bureau 
through the channels indicated above. 

Upon the establishment of a project in the 
San Diego laboratory, the second type of liai- 
son, to bring about the necessary close local 
cooperation, was authorized by the Office of 
the Coordinator. For instance, the program of 
assistance in the selection and training of sound 
operators and officers was greatly facilitated 
by the establishment of direct channels of 
communication between the laboratory and the 


FACILITIES ORGANIZED UNDER DIVISION 6 


49 


sonar schools and Operational Training Com- 
mands on both coasts. Such arrangements were 
necessary for the conduct of day-to-day oper- 
ations, and proved most fruitful in the stimulus 
they afforded both civilian and naval partici- 
pating groups. The responsible OSRD officers, 
the naval coordinating office, and the interested 
bureaus and commands were kept informed of 
the progress of all undertakings through the 
periodic reports issued by the laboratory. 


laboratory’s activities directed toward one or 
another aspect of prosubmarine warfare, the 
visits to the laboratory of Admiral C. A. Lock- 
wood, Jr., Commander Submarine Force Pa- 
cific Fleet, and his interest in many of the 
devices under development greatly stimulated 
this part of the program. By the middle of 
1944, the laboratory had representatives in the 
Pacific area attached to the submarine com- 
mand almost continuously, and a newer and 



Figure 12. Aerial view of the laboratory buildings located near the West Coast Sound School. 


Late in 1943 it became apparent that the 
success of our military operations justified a 
careful reconsideration of the projected pro- 
gram. Beginning in the latter part of 1943 and 
tor the remainder of the period of active work, 
the diminishing threat of submarine action and 
the great activity of the submarine force in 
the Pacific, caused the prosubmarine aspects of 
the laboratory program to assume major im- 
portance. This aspect of the laboratory’s work 
was promoted most effectively by the increased 
intimacy of working relationships with the 
Submarine Desk of the Bureau of Ships and 
the ComSubPac. With more than half of the 


closer relationship with the Bureau and the 
Navy laboratory tended materially to reduce 
the formal administrative routine associated 
with the travel and assignment of laboratory 
personnel and equipment in connection with 
these duties. 

With the possible termination of World 
War II in view and considering the necessary 
period between initial research and combat 
employment, the desirability of associating this 
work with a permanent organization, rather 
than a temporary emergency agency such as 
OSRD, became increasingly obvious. Supervi- 
sion of the San Diego laboratory program was 


50 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


accordingly transferred to the Navy Depart- 
ment on March 1, 1945, and later, responsibility 
for the contractor’s work was assigned to the 
Bureau of Ships. 

Objectives. A consideration of the activities 
and procedures of this laboratory should be 
prefaced by a survey showing the growth of 
the organization from a small, loosely knit 
group of a score of scientists in the summer 
of 1941 to an integrated organization of some 
600 persons comprising physicists, engineers, 
geologists, psychologists, writers, artists, ma- 
chinists, draftsmen, and others by the summer 
of 1945. 

The original primary objective of the labora- 
tory was the prosecution of fundamental sonar 
studies. This conception controlled the initial 
selection of personnel and the organizational 
division. Subsequent developments and shifting 
emphasis raised work in the fields of antisub- 
marine and prosubmarine devices and training 
to a comparable level, and this was reflected in 
the organization. 

In the initial organization, the director was 
Dr. Knudsen, a man of wide experience in the 
field of fundamental acoustic investigation. The 
largest group of scientific personnel, concen- 
trated on underwater acoustics, was directed 
by Dr. L. J. Sivian, on leave from the Bell 
Telephone Laboratories. This group was re- 
sponsible for the fundamental measurement 
program as well as for the equipment necessary 
to its accomplishment. Another small group 
was headed by Dr. K. S. Van Dyke, on leave 
from Wesleyan University, whose special field 
had been piezoelectricity, a fundamental tech- 
nique in transducer design. These persons were 
concerned chiefly with the investigation and 
development of detection devices. The third 
group, with no nominal head, served largely as 
a consulting body and was concerned with 
many special methods and techniques that were 
suggested in the early conferences leading to 
the laboratory’s establishment. 

There was little change in organization for 
the next 6 or 8 months, although the number 
of employees increased to nearly 100 by the 
early spring of 1942. The division of responsi- 
bility remained approximately the same, except 
that a somewhat more detailed breakdown was 


made in the lower levels. In April 1942, Dr. 
Knudsen’s services were urgently requested for 
work with the central directing organization 
of NDRC, and he was relieved by Dr. Harnwell, 
Director of the Randal Morgan Laboratory of 
Physics and Chairman of that department at 
the University of Pennsylvania. Concurrently 
with the assumption by Dr. Harnwell of the 
directorship, conditions led to a rapidly increas- 
ing growth in the laboratory’s activities. By 
August 1942, approximately 200 persons were 
employed. 

Dr. Sivian and Dr. Van Dyke were both 
called away for other important work and 
gradually the organization shifted. In April 
1943, a training division was established under 
Dr. H. E. Hartig who supervised work at the 
Navy sonar schools at Key West and San Diego 
and device development work within the lab- 
oratory. The Fundamental Research Division, 
subsequently known as the Sonar Data Divi- 
sion, was headed by Dr. Carl Eckart who had 
cognizance of high- and low-frequency propa- 
gation programs and also of the Oceanographic 
Section which contributed directly to both of 
these. The Sonar Devices Division, under Dr. 
F. N. D. Kurie, had again expanded greatly 
and was concerned with all matters of combat 
device design. 

The following year represented a rapidly 
expanding period for the laboratory and by the 
autumn of 1944, it achieved its maximum size 
of approximately 600 persons. The laboratory 
population continued at about this figure until 
termination plans were put into effect. 

Also, at the request of the Navy, a substan- 
tial program of maintenance manual prepara- 
tion was undertaken, and the necessity of liai- 
son with the Bureau of Ships, the Executive 
Office of the Secretary of the Navy, Navy man- 
ufacturers, and publishing firms indicated that 
this activity should be established in the east. 
Dr. J. C. Morris of Tulane University was se- 
cured to take charge of this undertaking, and 
its geographic separation clearly indicated its 
establishment as a separate laboratory division 
whose work was closely related to that of the 
training division. Earlier experience of the lab- 
oratory led the director to assign a business 
director to this group from its inception, and 


FACILITIES ORGANIZED UNDER DIVISION 6 


51 


this materially improved the effectiveness of 
its operations on the other side of the continent. 

Engineering Division 

A major step in improving the effectiveness 
of the scientific divisions was the establishment 
of an engineering division under Dr. R. 0. 
Burns. Services such as drafting, electronics, 
and machine work were grouped together and 
operated as a unit in serving the needs of the 
scientific divisions. As the design of training 
and combat equipment advanced and prototypes 
were made for operational tests, the Devices 
and Training Divisions drew very heavily upon 
the Engineering Division. Certain other local 
services, such as the Photographic and Record- 
ing Laboratories, likewise reported to Dr. 
Burns and served the three scientific divisions 
about equally. The need for larger numbers of 
prototypes for testing and the necessity of 
supplying small numbers of units of train- 
ing equipment in particular led to the estab- 
lishment of groups concerned with extension 
engineering and contract consultation. These 
groups essentially expanded the facilities of 
:he laboratory by including those of manu- 
facturing plants in the San Diego and Los 
Angeles areas. Some of this work was done 
m purchase order and some on subcontract, 
md the program played an important part in 
;he ability of the laboratory to accede to the 
nany requests received throughout this period 
:or prototypes and service equipment by the 
!^avy. The extensive activities of the laboratory 
n this field were coordinated with similar 
phases of the work of other OSRD contractors 
)y R. J. Coe, transition aide to the chief of 
Section 6.1, NDRC. 

As has been mentioned, the scientific work 
vas carried out by three groups, (1) the Sonar 
3ata Division, (2) the Sonar Devices Division, 
md (3) the Training Aids Division. A brief 
lescription of each division will be given. 

Sonar Data Division 

The Sonar Data Division was concerned with 
undamental research, primarily directed to 
he investigation of all acoustic propagation 
)henomena. This was the chief specific assign- 
nent to the laboratory upon its initial organ- 


ization, and as the laboratory developed, ap- 
proximately one-third of the effort of the staff 
was directed to the work of this division. 

In addition to a broad program of acoustic 
measurements, a corollary oceanographic pro- 
gram was carried out which was essential to 
the proper interpretation and understanding of 
the acoustic results. A second subordinate phase 
of investigation lay in the field of psychoacous- 
tics because of the importance of hearing in all 
practical naval applications. 

The efficient conduct of the Navy and NDRC 
programs as a whole required the establish- 
ment of direct liaison between divisions within 
the laboratory and groups elsewhere in the 
country or abroad concerned with similar prob- 
lems. In the experimental work, close relations 
were maintained with the Scripps Institution 
of Oceanography and the Woods Hole Oceano- 
graphic Institution and also with the Sonar 
Analysis Group of NDRC which was continued 
later in association with the Bureau of Ships, 
Code 940. This latter group had the general 
responsibility of integrating the work of the 
contractors in basic sonar research, and later 
assembled and issued a number of the Sum- 
mary Technical Reports covering the entire 
program. 

In addition to research cooperation, external 
connections were established for making the 
results of the program available directly to 
those naval offices and commands most directly 
concerned. Charts of various types prepared 
in the laboratory were submitted to the Hydro- 
graphic Office for official issuance. In some 
cases, and prior to such issuance, charts pre- 
pared by hand were furnished directly to 
ComSubPac. Also, in the bathythermograph 
program, direct liaison was maintained with 
the Service forces of the Pacific fleet, and the 
Hydrographic Office and Bureau of Ships were 
kept informed of these activities as they de- 
veloped. 

Sonar Devices Division 

As has been indicated, the Sonar Devices 
Division grew somewhat more slowly than the 
Data Division because of the initial philosophy 
under which it was presumed that the develop- 
ing and designing of combat devices could be 


52 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


carried out more effectively in eastern labora- 
tories. It soon became apparent that sugges- 
tions for such devices emerged naturally from 
the scientific program, and after a few unsuc- 
cessful attempts to transplant these to another 
laboratory, it was appreciated that nascent 
ideas were too nebulous to withstand the long 
transcontinental trip. In consequence, the al- 
ternatives were to disregard suggestions of 


operation, the division was concerned almost 
exclusively with antisubmarine sonar devices, 
where its role was somewhat secondary to that 
of the eastern laboratories. During the last two 
years of the contract, however, its efforts were 
redirected to the prosubmarine sonar and coun- 
termeasures fields, and here a number of fac- 
tors combined to make its contribution particu- 
larly effective. 



Figure 13. Sweetwater Lake transducer calibration station showing shore facilities and barges. 


UCDWR or to make provision within the pro- 
gram of the laboratory for the development of 
these ideas, at least to the stage where they 
could be taken up by other groups without 
serious loss of continuity. The second alterna- 
tive was wisely adopted, and after a year or 
two of operation, the Devices Division actually 
assumed somewhat the largest role in the lab- 
oratory’s activities. 

In distinction to the Data Division, the em- 
phasis of this work was on design, development, 
production, installation, and operational test- 
ing. During the first years of the laboratory’s 


Owing to the smaller number of submarines, 
as compared with surface vessels, the labora- 
tory’s scale of production could be much more 
effectively utilized by the Navy. The general 
level of technical interest and competence of 
the submarine forces were particularly high and 
enabled the establishment of intimate profes- 
sional relationships between the scientists and 
submarine officers. This had a marked effect on 
the promotion of joint experimental and devel- 
opment programs. 

For a long time the Devices Division was 
associated with the engineering services of the 


FACILITIES ORGANIZED UNDER DIVISION 6 


53 


laboratory, and throughout the entire life of 
the contract the effect of this could be clearly 
noted. The groups concerned with the design 
and development of crystal and other trans- 



Figure 14. Barge at El Capitan Lake which was 
used primarily for proving sonar decoy devices. 

ducers remained a part of the Devices Division, 
and the testing and calibrating stations were 
likewise sections under this division through- 
out the laboratory’s existence. These groups 
contributed most directly to the sonar and 
countermeasures projects in hand by the De- 
vices Division, but they were also of broad 
general use to the Training and Data Divisions 
as well. Cooperative work with the latter divi- 
sion has been briefly touched upon earlier and 
the relationship with the Training Division 
was equally close. One of the first major devel- 
opment undertakings of the laboratory was in 
the field of practice targets, and here the con- 
duct of the work was actually in the hands of 
the Devices Division although it constituted 
essentially a training function. On many other 
occasions, mutual services were performed by 
these divisions. These became evident formally 
on the adoption of laboratory-developed devices 
by the Navy and the institution of training pro- 
grams for operators of them at the sound 
schools or training commands. 

The external liaison of this division was 
almost as extensive as that of the Data Divi- 
sion. The work was integrated with that 
of eastern laboratories through Section 6.1, 
NDRC, and the maintenance of adequate chan- 
nels of communication with the Bureau of 


Ships required the almost constant presence 
of one or another member of this division in 
Washington. In procurement and manufactur- 
ing matters, the transition aide of NDRC was 
frequently utilized, and the services of more 
distant manufacturers were drawn upon. Di- 
rect naval liaison became particularly impor- 
tant in connection with the submarine work, 
and the OLA and Sound Beacon programs ne- 
cessitated the continuous retention of labora- 
tory representatives at west coast Navy Yards 
and in Pearl Harbor, and led to many indi- 
vidual trips farther into the Pacific. 

Training Aids Division 

The developments leading to the establish- 
ment of a training aids division have been 
indicated previously, and as the work pro- 
gressed the division assumed a definite char- 
acter presenting a number of points of contrast 
with the Data and Devices Divisions. 

The operation of the Training Division as a 
whole is outlined in more detail in a separate 
chapter, but the actual method of bringing the 
laboratory’s contribution most effectively to 
bear on the Navy’s problems in this field de- 
serves brief mention here. The need for train- 
ing assistance was sometimes appreciated first 
within the Navy itself, sometimes at a sonar 
school or training command, sometimes within 
an evaluation command such as AsDevLant, 
and sometimes by the civilian scientists them- 
selves. The wide area from which these sugges- 
tions might emanate points clearly to the ne- 
cessity for a widely dispersed but closely inte- 
grated and flexible organization. To some ex- 
tent, integration was supplied by the Selection 
and Training Committee of Division 6, NDRC, 
and to some extent by the staff of the Com- 
mander-in-Chief. Upon the recognition of a 
need for a device, conferences between all per- 
sons properly concerned led to the establish- 
ment of a laboratory program for design and 
development. Subsequently, with the continuing 
cognizance of everyone, initial units were fur- 
nished to training or evaluation commands and 
preliminary instructional programs were un- 
dertaken. As a result of careful and critical 
study, errors and inadequacies were recognized 
and steps taken to effect the design and assist 


54 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


in the procurement of an adequate supply of 
the device for Navy use. Thereafter the train- 
ing-techniques group continued to work closely 
with training commands, utilizing a device in 
the perfection of instructional techniques. The 
nature of the external liaison implied in the 
operation of this division is sufficiently clearly 
indicated in the summary of its method of op- 
eration, and it is clear that the maintenance of 
close and harmonious relationships between a 
wide variety of civilian specialists and naval 
officers played a particularly important role in 
this aspect of the laboratory’s undertakings. 

Engineering Services Division 

The laboratory had two chief service divi- 
sions, the Engineering Services Division and 
the Business Division. Since we are concerned 
here primarily with the technical facilities, 
these will be described in more detail. It be- 
came apparent early that technical services 
could best be furnished by a division of the lab- 
oratory independent of those persons charged 
with the conduct of particular scientific prob- 
lems. This separation into scientific and service 
activities was not entirely clean-cut in all cases, 
and, in particular, it was by no means true 
that scientific personnel were employed exclu- 
sively in the scientific divisions and nonscien- 
tific personnel in the service divisions. The 
Engineering Services Division in particular 
included many people of high technical skill. 
As instances, the Design and Drafting Depart- 
ment, the Electronics Laboratory, and the Re- 
cording Laboratory were staffed by specialists 
engaged in work essentially comparable to that 
of equipment designers and electronic engi- 
neers in the Training and Devices Division. The 
service groups, however, were distinguished 
by the assisting role which they played in col- 
laboration with the scientific divisions. Partic- 
ular jobs were assigned to them on job-order 
requisitions from project leaders, and contin- 
uity of occupation of the several subdivisions 
of the service groups contributed greatly to the 
efficiency with which their work was per- 
formed, besides adding importantly to the flex- 
ibility of the laboratory’s operations. 

The Engineering Services Division per- 
formed a wide variety of functions for the 


scientific groups of the laboratory, and, in 
magnitude, its payroll was approximately one- 
quarter that of the laboratory as a whole. 

Design and Drafting. One subdivision of the 
Engineering Services Division, concerned with 
the operation of all local engineering service 
activities, was the Design and Drafting De- 
partment which was drawn upon by all divi- 
sions almost equally for design work involved 
in their programs. Central records of prints 
and drawings were kept by this group which 
also assumed responsibility for their proper 
classification and custody. This was of material 
assistance in bringing about uniformity of pro- 
cedures and also was invaluable in cooperation 
with the Extension Engineering and Subcon- 
tract Departments when the assistance of ex- 
ternal manufacturers had to be enlisted. 

Machine Shop. The machine shop was much 
the largest of the local service groups and, to- 
gether with the sheet metal and paint shops, 
formed a mechanical unit for the production 
of experimental equipment, trial models, and 
prototypes, in addition to assisting on many 
occasions with urgent production work which 
could not be produced to specification or in time 
by commercial shops in the area. 

Electronics Laboratory. The Electronics Lab- 
oratory, as its name implies, designed, fabri- 
cated, and tested electronic components of 
equipment required by the scientific divisions, 
collaborating closely with the Drafting and 
Mechanical Construction Departments as was 
required in the construction of the units. Skilled 
electronic designers were of particular assist- 
ance to the Sonar Data Division because few 
of its personnel with the requisite electronic 
experience were available for the design of the 
equipment required for their measurement pro- 
gram. All divisions made equal use of the 
Electronics Laboratory and the Transformer 
Laboratory for the actual construction of ex- 
perimental and service equipment. 

Recording and Communications. The other 
subdivisions of the Engineering Services Divi- 
sion were more or less independent units less 
closely integrated with engineering services 
than with the programs of particular scientific 
projects or routine services to the administra- 
tive group of the laboratory. The Recording 


FACILITIES ORGANIZED UNDER DIVISION 6 


55 


Laboratory, for instance, divided its time nearly 
squally between work for the Sonar Data Divi- 
sion and the Training Aids Division. Occasion- 
ally, work was done for the Devices Division 
as well, but the routine recording of sea results 
af the transmission program and the construc- 
tion of training recordings occupied most of 
the time of this group. It rendered an inval- 
uable service through these two associations 
and demonstrated the essential role played by 
skilled recording personnel, in sonar research 
and training. The connection between the Re- 
cording Laboratory and the Communications 
Group was a close one, as much of the work 
handled by both involved the receipt of radioed 
information from laboratory and naval vessels 
at sea. The Communications Group was also 
inked by common interests and personnel with 
the Electronics Laboratory, and the closest co- 
operation was maintained between these groups 
and the local naval communications authorities. 

Photographic Laboratory. The Photographic 
Laboratory was initially instituted as a sub- 
iivision of the Engineering Services Division, 
out its work was divided about equally between 
assisting the scientific divisions on the one hand 
and the reports group on the other. Some as- 
sistance was rendered the Personnel Depart- 



Figure 15. The USS Jasper (PYC13) used 
principally by the Sonar Data Division for deep 
sea measurements. 


nent in the taking of employee photographs 
and other routine services, and a special pro- 
gram was set up for the development of oscil- 
ographic recordings taken by the Sonar Data 
Division. However, the greater portion of the 


time was devoted to photographing devices in 
various stages of completion and in furnishing 
suitable prints for all types of reports. At a 
later stage of the laboratory’s operation, this 
group was transferred to the Publications Di- 
vision, as this proved to be a more efficient 
arrangement when the laboratory effort was 
largely directed to the reporting of its previous 
program. 

Marine Facilities. The Engineering Services 
Division also had charge of the equipping and 
maintenance of the laboratory’s marine facil- 
ities. The E. W. Scripps and the M. V. Torqua , 
which were not naval vessels, required a cer- 
tain amount of ordinary marine maintenance, 
and this was furnished during most of the 
laboratory’s existence by a small group organ- 
ized for this purpose. The general supervision 
of personnel aboard these ships was also in the 



Figure 16. The E. W. Scripps also used for deep 
sea work. 


province of the Engineering Services Division. 
These two vessels, and also the naval vessels 
assigned to the program, carried extensive in- 
stallations of scientific apparatus for the con- 
duct of the various projects. In general, this 
was designed and built by the Engineering 
Services Division and then installed and main- 
tained by engineers assigned to the Marine 
Facilities Department of this division. These 
men served essentially as equipment curators 
aboard the vessels. Their services were indis- 
pensable in maintaining the equipment in oper- 
ating condition and in adapting it to the day- 


56 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


to-day requirements of the various scientific 
programs which shared its use. 

Procurement. One of the most important 
functions of the Engineering Services Division 
was that of procuring devices constructed to 
laboratory specifications from suppliers both 
in the Southern California area and elsewhere. 
When designs had reached a stage at which no 
further research or development was antici- 
pated, units were procured by purchase order 
in suitable quantity for operational test. When 
it was anticipated that further research would 
be required, the Government’s interests were 
protected by the procuring of devices under 
subcontract. The group of engineers forming 
the Extension Engineering and Subcontract 
Department of the Engineering Services Divi- 
sion performed the essential functions of as- 
sisting the Purchasing Department in locating 
suitable suppliers, interpreting laboratory spec- 
ifications to them, and furnishing technical ad- 
vice and supervision in the course of the man- 
ufacturing program. Through this section, the 
laboratory’s ability to provide those services 
requested by the Navy was greatly expanded. 
It would have been impossible to provide the 
necessary space and facilities in the laboratory 
itself for the manufacturing programs that 
were from time to time undertaken, and had 
the attempt been made to do so, it would have 
reacted unfavorably on the experimental and 
pioneering development which was the chief 
obligation of the laboratory. On the other hand, 
adequate naval evaluation required the provi- 
sion of many units of different types of devices, 
and this was accomplished both expeditiously 
and economically through enlisting the services 
of local manufacturers whose efforts were in- 
tegrated with the laboratory’s program through 
the activities of the Engineering Services Di- 
vision. 


The Harvard Laboratory 
Establishment and Objective 

The operations of the Harvard Underwater 
Sound Laboratory [HUSL] covered the period 
from June 5, 1941 to January 31, 1946. The 
laboratory was established under a contract 


between NDRC and Harvard College. It was 
continued under a renewal contract which in 
turn was extended by 14 supplements. 

Harvard Group Proposed. The establishment 
of HUSL grew indirectly out of work begun in 
December 1940 by Massachusetts Institute of 
Technology [MIT] under a direct Navy con- 
tract. Learning that research having to do 
with underwater warfare was being undertaken 
by a division of NDRC, leaders of the MIT 
group suggested that there might be a valuable 
program which could be conducted under Har- 
vard auspices. In a letter of June 5, 1941, Fred- 
erick V. Hunt, associate professor of physics 
and communications engineering at Harvard, 
and Philip M. Morse, professor of physics at 
MIT, wrote T. E. Shea, director of the New 
London laboratory, outlining certain types of 
investigation which they believed might be 
prosecuted advantageously. Work at the lab- 
oratory which was later to be known as the 
Harvard Underwater Sound Laboratory began 
almost immediately and was soon formalized 
under a contract which bore the effective date 
of the original proposals, June 5, 1941. Dr. 
Hunt was named director. 

Phases of the Program. During the first 
phase of the laboratory’s program, which lasted 
from its establishment until July 1, 1942, the 
work of the laboratory divided itself rather 
naturally into three parts. First, there was 
urgent need to increase the effectiveness of 
submarine detection equipment already in- 
stalled in Navy ships. Second, it was desirable 
to devise and experiment with new forms of 
equipment which offered the possibility of 
greatly improved performance. Lastly, in the 
fall of 1941, a third major project was estab- 
lished when the laboratory was requested to 
undertake work which it was hoped might lead 
to the construction of antisubmarine ordnance 
which would home itself on its target by acous- 
tic means. 

The first period, as might be expected, was 
largely one of exploratory study, of rapid 
growth in the number of employees, and of 
expansion of facilities for carrying on research. 

The fact, however, that the work of the lab- 
oratory was to a great extent exploratory did 
not mean that significant developments were 


FACILITIES ORGANIZED UNDER DIVISION 6 


57 


not achieved. During this early phase of the 
program, the bearing deviation indicator (de- 
scribed in a later part of this volume) was 
developed and successfully tested. This device, 
auxiliary to current submarine detection gear, 
improved the accuracy and speed with which 
a target could be located. Other studies and 
experimental work during the first year of 
HUSL’s operation, provided the basis for two 
other important developments which matured 
later. One of these was the antisubmarine 
acoustic mine ; the other was a type of scanning 
sonar gear which was continuously alert in all 
directions. 

A move to new and larger quarters in Har- 
vard’s Hemenway Gymnasium marked the be- 
ginning of the second phase of the HUSL pro- 
gram which was to extend from July 1942 
through December 1943. 

Work continued on the development of im- 
proved forms of sonar equipment, but at the 
same time the intensity of the enemy’s sub- 
marine activities along the Atlantic coast made 
imperative the development of improvements 
immediately applicable to detection equipment 
already installed on convoy escort vessels. A 
number of improvements of this type were 
completed, and HUSL provided manufacturers 
with technical assistance in their production 
and provided the Navy with assistance in in- 
stalling them and in training naval personnel 
to use them. 

Work on the acoustic mine was continued 
and before the end of 1942 the device had been 
successfully air-launched and sent in pursuit 
of artificial targets. By February 1943, produc- 
tion units had become available for full-scale 
tests and late in the spring of 1943, the weapon 
had been put into operational use. 

The third period of the HUSL program ex- 
tended from January 1944 to the termination 
of the contract in January 1946. This period 
saw an addition to Hemenway Gymnasium of 
almost double the available working space, and 
saw the laboratory reach the peak of its ac- 
tivity in the summer and fall of 1944. 

Scanning sonar was developed to the point 
where the Navy felt justified in deciding to 
incorporate it as a feature of “ultimate” sonar 
equipment. Parallel work on the acoustic con- 


trol of standard Navy torpedoes brought results 
which justified starting manufacture on one 
full-size acoustic torpedo for launching from 
submarines. Further work led to the success- 
ful application of acoustic control to an air- 
launched steam torpedo and a high-speed elec- 
tric torpedo, and to the advanced development 
of acoustic control by echo ranging, a system 
more difficult for an enemy to counter. 

As the termination of the HUSL contract 
approached, the development projects which 
were still active were progressively transferred 
to the Navy. The sonar development program 
was transferred to the Naval Research Labora- 
tory, and the torpedo development program to 
the Ordnance Research Laboratory at Penn- 
sylvania State College. 

Personnel 

As in all other wartime laboratories, one of 
the most acute problems with which HUSL had 
to contend was that of securing adequate num- 
bers of competently trained personnel. 

Recruiting. The recruiting of personnel suf- 
fered under many handicaps. For example, in 
attempting to persuade a likely candidate to 
join the HUSL staff, security reasons might 
well make it impossible to describe the work 
of the laboratory in sufficiently convincing de- 
tail to make it clear that it was more important 
than the work the candidate was then doing. 

The management of HUSL used every pos- 
sible means and device to secure lists of poten- 
tial research workers. In the end, it usually 
came down to a matter of leg work, with a 
recruiting officer from the laboratory going 
into the field to track down, interview, and pass 
judgment on personnel who seemed to show 
promise. 

Salaries. The fact that employment with 
HUSL was for the duration only and that it 
meant moving mature scientists from one work- 
ing environment to another made the deter- 
mination of salaries a complex problem. In 
fixing a starting salary numerous factors had 
to be considered, including the employee’s edu- 
cational background, his training and experi- 
ence, previous salary history, the responsibil- 
ities which he would have in the HUSL organ- 
ization, and the personal complications which 


58 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


would result from his transfer to a new environ- 
ment. The governing principle was that the in- 
dividual should be transplanted without im- 
posing on him a financial penalty on the one 
hand, or offering him a financial reward on the 
other. 

It was the policy of the laboratory manage- 
ment to conduct periodic salary reviews, usually 
at intervals of 6 months, at which time possible 
adjustments of previous salaries could be made 
in the light of an employee’s proved ability to 
handle more important assignments. 

The salary policy covering the employment 
of the service staff of the laboratory (as dis- 
tinct from the scientific staff) was governed 
in large part by conditions in the local labor 
market. In recruiting the service staff and fix- 
ing service salaries the Office of Personnel 
Relations of Harvard University provided in- 
valuable assistance by giving applicants a pre- 
liminary screening and by correlating the sal- 
ary scale of HUSL with the salary rates pre- 
vailing in other laboratories operating at 
Harvard under OSRD contract. 

Scientific-Service Staff Ratio. One of the ad- 
ministrative problems involved in the manage- 
ment of a research laboratory is that of deter- 
mining the proper ratio between the number 
of scientific investigators and the service staff 
required to support their efforts. During the 
early months of HUSL’s operation, it was not 
unusual to find scientists with doctor’s degrees 
doing their own drafting, constructing and as- 
sembling their own apparatus, wiring their 
own electronic chassis, and writing their own 
reports in longhand. It did not take long to 
recognize that this was a waste of talent. A 
recruiting program, by July 1942, had brought 
the ratio of supporting service staff to scien- 
tific staff to 1/3. 

Women Employees. The failure of Selective 
Service to provide unequivocal deferments 
for scientific personnel, plus the general scar- 
city of available male workers, early led the 
laboratory to employ women as drivers, mes- 
sengers, technicians, and apprentice machin- 
ists. Women electronic technicians were in 
general given on-the-job training. A system of 
employing novice girl technicians at electronic 
salvage, that is, the unwiring of experimental 


chassis for the recovery of components, proved 
highly satisfactory in that it showed their su- 
pervisors whether or not they possessed manual 
dexterity and were generally reliable and suited 
to electronic wiring work. 

A complete cumulative roster of all those 
employed by HUSL included a total of 818 per- 
sons. The peak of employment occurred in 
August 1944 when the total laboratory personnel 
reached 462. Of the total staff of 818 employees, 
238, or 29 per cent, had college degrees. Of the 
158 research associates, 96 per cent had college 
degrees, 58 per cent had masters’ degrees, and 
30 per cent had doctors’ degrees. 

Physical Plant 

One of the premises underlying the original 
proposal for research on underwater sound at 
Harvard University was the availability of a 
limited amount of space in the Cruft Labora- 
tory and the Research Laboratory of Physics. 
Early work was conducted in the large “battery 
room,” 35x51 ft, in the basement of the latter 
building. Procurement was handled through 
the regular university channels. 

As new recruits were added to the laboratory 
staff the research work expanded into other 
rooms adjoining the battery room, but the pro- 
gram grew at such a rate that by the spring 
of 1942 experiments were being conducted in 
space providing less than 60 sq ft per capita. 
A survey of other available buildings showed 
that Hemenway Gymnasium, erected in 1938 
to replace an older building of the same name, 
would be adequate to house the expanded ac- 
tivities of the Underwater Sound Laboratory. 
Plans for altering the gymnasium went for- 
ward speedily. 

Hemenway Gymnasium. Hemenway Gymna- 
sium comprised a tier of six squash courts 
below ground level, another tier of six squash 
courts above ground level, and a top floor con- 
taining a regulation basketball floor and a bad- 
minton court. Each tier had three squash courts 
on each side of a mezzanine corridor. By erect- 
ing temporary floors to carry these mezzanine 
levels across the courts, the floor area available 
in the squash court section of the building was 
doubled and ultimately contained about 24,000 
sq ft. Somewhat later, advantage was taken 


FACILITIES ORGANIZED UNDER DIVISION 6 


59 


of the high ceiling of the baskball floor to sur- 
round the floor with a balcony 13 ft wide, and 
at level of this balcony a temporary floor was 
built over the badminton court. Thus in addi- 
tion to the two floors below ground level, the 
gymnasium was remodeled so as to provide four 
floors above ground. 

Gannett House. As wartime requirements 
reduced the number of law students in resi- 
dence, HUSL was able to obtain the use of an 
adjacent frame building, Gannett House, pre- 


the addition was ready for occupancy early in 
March 1944. The additional space provided by 
the annex nearly doubled the floor area avail- 
able for the laboratory’s research and develop- 
ment work. 

Field Stations. Soon after the establishment 
of the laboratory, two small field stations were 
set up. One of these was at the tip of Pier 1 in 
East Boston and the other at Pier 8 in the 
Charlestown Navy Yard. 

Shortly afterward, difficulties encountered 



Figure 17. Gannett House and Hemenway Gymnasium before and after erection of the annex to Hemenway. 


viously occupied by certain law school activities. 
Reception, personnel, business, and procure- 
ment of HUSL were transferred to Gannett 
House on July 19, 1943, and convenience of 
access was assured by the erection of a covered 
overpass connecting the second floor of Gan- 
nett House with the fifth floor of Hemenway 
Gymnasium. 

Other minor additions to the laboratory 
building were made from time to time and 
warehouse space for unclassified material was 
acquired in other university buildings. All these 
steps, however, were insufficient to keep up 
with the expansion of the laboratory’s scien- 
tific personnel required by the continuing pres- 
sure to accelerate the completion of vitally 
needed developments. 

Hemenivay Annex. As a result, authoriza- 
tion was sought and granted in November of 
1943 for the construction of a large temporary 
annex to Hemenway Gymnasium. Temporary, 
factory-type wooden construction was used and 


in the use of these stations made it necessary 
to construct a measurement barge, 61x21x5 ft. 
This barge, delivered in April 1942, provided 
enclosed working space including a large well 
for lowering test equipment into the water. 
Initially, it was operated in the slip of the 
Hodge Boiler Works in East Boston, but the 
high ambient noise level produced by ship con- 
struction activities at the neighboring Charles- 
town Navy Yard made this location unsuited 
for acoustical measurements. 

It was arranged, therefore, that the barge 
should be anchored in the lower Charles River 
Basin, where it stayed throughout the remain- 
der of the war as the Charles River Calibration 
Station. In September 1942, a smaller barge 
was provided which was later tied permanently 
to its larger predecessor in order to provide 
auxiliary well space for tests on standard pro- 
jectors. 

The Charles River Basin furnished unusually 
favorable conditions for acoustic measurements 



60 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


in the supersonic frequency range. The lower 
part of the Basin, in which the measurement 
barges were anchored, is approximately three- 
quarters of a mile wide, and over most of this 
width, the depth of the water is approximately 
20 ft. The soft mud of the bottom provided a 
high degree of acoustic absorption and there 



Figure 18. The barge measurement station in 
the lower Charles River basin. 


was practically no man-made underwater inter- 
ference. A waterproof cable from shore pro- 
vided reliable power. 

Some of the early experiments on the anti- 
submarine mine were conducted off Nahant, 
Massachusetts. Running tests and preliminary 
steering trials were conducted there and, by 
arrangement with the Naval Air Station at 
Squantum, it was possible to carry out trials 
leading to the development of successful meth- 
ods of dropping mines from aircraft. In May 
1943, the Board of Selectmen of the town of 
Nahant gave HUSL semi-exclusive use of the 
town dock for experimental work. Permission 
was obtained to make necessary alterations, in- 
cluding the erection of a temporary building on 
the pier end of a derrick for handling the 
heavy torpedo bodies. 

Another measurement station was con- 
structed at Spy Pond in Arlington, Massachu- 
setts, 31/2 miles distant from the laboratory. 
The Spy Pond Station relieved the Charles 
River Basin Station of some of the load of 


measurement work. The facilities at Spy Pond 
included a ramp extending 36 ft from the 
shore to the 32x20 ft measurement building. 
Two heavy steel girders framed a well which 
provided an unobstructed working area 30x4 ft. 
The handling facilities were sufficiently rugged 
to cope with full-size torpedo bodies. 

Since cold weather arrives in the early fall 
off the New England coast, it became apparent 
in September 1942 that a warm, deep-water site 
for the year-round conducting of experiments 
with homing torpedoes was imperatively 
needed. The result of an extensive survey of 
possible sites was the determination to locate 
the new installation near the Coast Guard Sta- 
tion at Fort Lauderdale, Florida. 

The Navy Bureau of Ordnance leased the 
peninsula constituting the eastern end of Fort 



Figure 19. Fort Lauderdale Station (U.S. 

Navy) . 

Lauderdale’s 15th Street, which had been occu- 
pied by a fishing resort and a small fuel dock 
operated by the Gulf Oil Company. The estab- 
lishment created at this location was operated 
entirely by the Navy and was known as the 
Naval Ordnance Unit. 

Operations at Fort Lauderdale commenced 
on September 8, 1942, and provided research 
and field testing facilities, not only for HUSL, 
but for groups from the Bell Telephone Labora- 
tories and General Electric Company, operat- 
ing under NDRC contracts, and for a Brush 
Development Company group operating under 
a Bureau of Ordnance contract. 

Floating Facilities. In addition to shore sta- 
tions and barges, seagoing facilities were 



FACILITIES ORGANIZED UNDER DIVISION 6 61 


needed and these were provided through use of riod, the number of HUSL employees grew 
USS Galaxy, on which an experimental model from 3 to 125. They were predominantly re- 
of QCL equipment was installed in January search personnel. The members of the group 
1942. Later the need for additional facilities worked together in a small area and it was 
for the sea testing of sonar equipment led to comparatively easy to keep everyone informed 
the purchase in June 1942 of the Aide de about the progress of the work being done and 
Camp, a 110-ft twin-screw diesel yacht which to maintain continuing contact with NDRC 
was provided with two wells and other hull and the Navy. There was little need for much 

Table 3. Vessels of the HUSL fleet. 

Vessels 

Type 

Overall 

length 

(ft) 

Load 

water 

line 

(ft) 

Beam 

(ft) 

Draft 

(ft) 

Cruising 

speed 

(knots) 

Power plant 

Navy craft 








USS Galaxy 

Yacht 

130 

121% 

21 y 3 

7 

11% 

Two 245-hp Winton 

Built 1930 by Pusey 







diesel engines, 4-c 6 

and Jones, Wilming- 







cylinder 

ton, Del. 








Flying Cloud 

Launch 

50 

47 

13 

4 

6 

D. D. Buda 60-hp diesel 

Converted motor 






Max. 9 

engine 

launch. Duty rating 








“work boat” 








HUSL craft 








Questor 

Motor sailer 

31 

34 

11% 

4y 6 


Chrysler ace gasoline 

Purchased May 1942 







engine 70-hp 6 cylin- 








der 

Aide de Camp 

Diesel yacht 

110 

102 

is y 6 

6 


Two 200-hp Winton 

Purchased June 1942 

(twin screw) 






diesel engines, 4-c 6 








cylinder 

Tommy 

Sedan cruiser 

30 

29 

8y 2 

1% 

21 

Two 95-hp Chrysler 

Purchased May 1943 

(twin screw) 






engines, 6 cylinder 

Juldi Walla II 

Motor sailer 

40 

38 

12%2 

% 


One 135-hp direct-drive 

Purchased December 







Chrysler engine, 8 

1943 







cylinder 

Tyler Too 

Barge 

61 


21 




Purchased May 1942 








Tippecanoe 

Barge 

31 


14 




Purchased July 1942 









openings for experimental work. Later, other 
smaller vessels were added. The entire HUSL 
fleet is shown in the following table. 

Organizational Development 

As has been noted, the program of HUSL 
was divided chronologically into three periods, 
the first extending from June 1941 to July 1942, 
when the laboratory moved to its quarters in 
Hemenway Gymnasium; the second extending 
from July 1942 through December 1943, when 
the annex to Hemenway Gymnasium became 
available; and the final period from January 
1943 to the termination of the laboratory con- 
tract at the end of January 1946. 

Informal Beginning. During the initial pe- 


attention to be paid to a more formal organiza- 
tion. 

As the research staff grew, the individual 
project groups developed their own group lead- 
ers and these constituted an informal commit- 
tee providing a channel by which administra- 
tive decisions could be made known to the staff 
as a whole. This system of administration func- 
tioned adequately, a contributing factor being 
the lack of need for the establishment of any 
management services, since procurement, jani- 
tor and telephone service, and the many other 
service functions were performed by the Uni- 
versity’s Departments of Physics and Com- 
munications Engineering. 

The removal to Hemenway Gymnasium 


62 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


brought a full realization of the extent to which 
the laboratory had been the beneficiary of these 
service facilities. Supplying them on the lab- 
oratory’s own account created many heavy 
administrative problems. 



Figure 20A. USS Galaxy (IX-54), experimental 
facility of the Bureau of Ships, provided a vehicle 
for experimental work in all phases of HUSL’s 
sonar program. 

Administration by Committee. The second 
period, following the move to Hemenway Gym- 
nasium, might be designated as “Administra- 
tion by Committee.” Administrative functions 
were allocated in such a way that two or more 



Figure 20B. The Aide de Camp, an HUSL ex- 
perimental yacht used for the early experimental 
work in the scanning sonar development program. 


individuals shared primary and secondary re- 
sponsibilities with respect to the administra- 
tion of each service function. By this arrange- 
ment, it was nearly always possible for a 
troubled staff member to find without delay a 
member of the administrative group who had 
sufficient authority to deal with his particular 
problem. 

Early in 1943 the various project group 
leaders were organized into an administrative 


council, the members of which divided among 
themselves the multitude of administrative 
duties which must be performed if a laboratory 
group is to operate successfully. 

But as might have been anticipated, this 
method of organization and administration 
began to reveal its inadequacies as the labora- 
tory population continued to grow. With the 
advice of Division 6 and Harvard University 
officials, a reorganization was effected in Janu- 
ary 1944 to provide for a more systematic allo- 
cation of responsibility for various phases of 
the laboratory program. 

Organization by Divisions. Under the new 
plan of organization, the HUSL development 
program was broken down into two major tech- 
nical divisions, Sonar and Ordnance, each un- 
der an associate director. A technical service 
division, under a technical service manager, 
was responsible for supervising the operation 
of the various machine and electronics shops, 
the design and drafting departments, and the 
other technical units which provided services 
to the two research divisions. 

The responsibilities of the Personnel Office, 
which previously had been concerned only with 
the service staff, assumed in addition the chore 
of recruiting research and technical personnel. 
The Business Office, in addition to its function 
of accounting and procurement, assumed com- 
plete responsibility for the maintenance and 
improvement of the laboratory plant. 

An editorial division was created which had 
responsibility for the Document Library and 
for the editing, printing, and publication of all 
laboratory reports, instruction manuals, and 
other documents prepared for external distri- 
bution. The laboratory’s patent attorney, who 
was responsible for the preparation of the in- 
vention reports required by the OSRD contract, 
served also as security aide to the director. 

In retrospect, those responsible for the man- 
agement of HUSL believe that organization by 
major technical divisions might profitably have 
been introduced much earlier in the labora- 
tory’s growth. They are equally convinced that 
the organization’s plan as finally evolved could, 
with only minor modifications, serve for the 
effective conduct of an even larger activity. 
The “happy family” plan of organization char- 


FACILITIES ORGANIZED UNDER DIVISION 6 


63 


acterizing the middle period of HUSL history is 
the sort that provides a congenial atmosphere, 
but it is applicable only to a group small enough 
so that all participants in the administration 
can remain continuously informed concerning 
all phases of the effort. 



Figure 21. The engineering room, the machine 
shop, and the main drafting room. 


If HUSL’s tardiness in realizing the need for 
a more formal organization requires apology, 
it is to be found in the fact that the members 
of the administrative staff were caught up in an 
activity far more complex than any to which 
they had been previously exposed, and that the 
progressive education of this group in manage- 
ment principles constituted a major, though 
anonymous, training project. 

Research and Development Program 

Since the major aspects of HUSL’s research 
and development program are dealt with in 
detail in other parts of this volume, only a brief 
review will be included here. 

The laboratory’s preliminary research pro- 
gram included sound-field surveys in which 
HUSL extended into the ultrasonic frequency 
range the survey measurements already being 
conducted under the MIT project. HUSL also 
did research on underwater acoustic impedance 
measurements and work to determine the 
depth of submerged submarines, the directivity 
of sound sources, and the possibility of devis- 
ing an echo-ranging system in which direc- 
tional control of the transmitting or receiving 
beam could be obtained by variation of fre- 
quency rather than by the mechanical training 
of a projector. The laboratory made an exten- 
sive survey of sonar literature. 

The development at HUSL of improvements 
for searchlight-type sonar equipment included 
the bearing deviation indicator, various auto- 
matic gain control systems, devices for utiliza- 
tion of the doppler effect, and other devices 
which are described in Part IV of this volume. 
Also discussed in Part IV is the development 
work by HUSL on scanning sonar equipment, 
sonar testing equipment, and equipment de- 
vised as training aids. 

In Chapter 9, the work of HUSL on trans- 
ducer development is discussed in some detail. 
The laboratory’s ordnance development pro- 
gram is covered in Chapter 13. 

The development of one device may properly 
be touched on here since it has administrative 
and financial as well as technical implications. 
This set of equipment was known as the beeper. 
In the practice firing of torpedoes a certain 
percentage did not perform according to speci- 



64 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


fixations and though the Navy attempted to re- 
cover them, a considerable number was lost. 
HUSL devised a noise-making mechanism 
which could be carried within the torpedo and 
a receiver to be installed on a boat patrolling 
for lost torpedoes. At current contract prices 
for naval torpedoes, the total value of the more 
than 700 “sinkers” recovered with the assist- 
ance of HUSL beeper equipment is almost equal 
to the total sum allocated for all operations 
under the HUSL contract. 

Costs 

The grand total of disbursement by HUSL 
was $7,233,900, of which $286,600 was ex- 
pended during the early formative period from 
June 5, 1941, to June 30, 1942. The remaining 
$6,946,300 disbursed from July 1, 1942, to 
January 31, 1946, breaks down as follows. 

Total salaries 45.8 per cent (of which 18.6 
per cent was for the salaries of research asso- 
ciates, 9.2 per cent for technicians’ salaries, 
and 18 per cent for the salaries of all others) ; 
expendable supplies, 26.1 per cent; capital 
equipment, 9.2 per cent; construction and 
building restoration, 8.2 per cent; miscellane- 
ous expenses, 6.8 per cent ; and overhead 
charges, 3.9 per cent. 

Interpreting these numerical data in another 
way, it may be said that it required approxi- 
mately $22,000 a year to hire a research asso- 
ciate, to supply him with supporting techni- 
cians and service staff, apparatus equipment 
and expendable supplies, and to defray all other 
costs (except rent and depreciation on the lab- 
oratory building) in connection with his work. 


3 ' 2 ’ 3 * * * 7 Airborne Instruments Laboratory 

As has been mentioned in an earlier chapter, 
Dr. L. B. Slichter had been interested in the 

detection of submarines by magnetic methods 
considerably before the formation of Section 
C-4 of NDRC. At the request of Doctors Col- 
pitts, Coolidge, and Mason, Dr. Slichter pre- 

pared a memorandum on this subject and on 

December 21, 1940, sent a copy of this memo- 
randum to Dr. Bush. The limitations of mag- 
netic methods were clearly realized but Dr. 


Slichter recommended that the method be thor- 
oughly explored. 

Dr. Slichter’s trip to England in April and 
May of 1941 with Dr. Tate gave him a broader 
picture of the antisubmarine problem and par- 
ticularly of the work that the British were 
doing in the field of magnetic detection. By the 
time he returned, Section C-4 had been estab- 
lished, and under a contract with Columbia 
University, he organized a group to undertake 
some preliminary investigations at MIT. Later 
the group working on this project was trans- 
ferred to the Naval Air Station at Quonset 
Point, Rhode Island. There, office and shop 
space was made available in land hangar No. 1. 
For flight test use, a PBY with pilot and crew 
was made available. Since the early work of 
this group was confined largely to the testing 
of equipment developed elsewhere, these facili- 
ties were completely adequate. Dr. D. G. C. 
Hare joined the group at this time and was 
later made director of the Airborne Instruments 
Laboratory. In the winter of 1941, development 
work on what proved to be the most successful 
solution to the problem was begun within the 
group at Quonset Point. This necessitated a 
considerable increase in personnel. In addition, 
shortly before our entry into World War II, 
equipment developed by the Gulf Research and 
Development Company in Pittsburgh had made 
successful tests with friendly submarines. With 
the outbreak of the war and the appearance 
of enemy submarines off our coast, a very 
marked interest in this was evidenced by the 
Navy. These two factors made it advisable to 
move the center of the activities to a place 
providing more space and which was less 
isolated than the Naval Air Station at Quonset 
Point. Accordingly, a survey of facilities adja- 
cent to large airports was made and in March 
of 1942 the center of activities was moved to a 
portion of the TWA hangar at LaGuardia 
Field, New York. All the facilities at Quonset 
Point were maintained but activities there were 
largely confined to the testing of equipment de- 
veloped at LaGuardia. 

Laboratory Facilities and Equipment 

In July 1942, the headquarters of the labora- 
tory were in a portion of the TWA hangar at 


( 




FACILITIES ORGANIZED UNDER DIVISION 6 


65 


LaGuardia Field with an experimental base at 
Quonset Point Naval Air Station, where about 
20 per cent of the scientific staff was stationed. 
Operational bases were maintained at the 
Lakehurst Naval Air Station, New Jersey, and 
Langley Field, Virginia. 





Figure 22. Main AIL buildings, 150 and 160 
Old Country Road, Mineola, N. Y. 


In September 1942, the lack of sufficient 
space necessitated a move to Mineola, Long 
Island, to occupy a building at 150 Old Country 
Road, and a residence at 92 Old Country Road. 
The official name then used was the Airborne 
Instruments Laboratory. Through an arrange- 
ment with the Long Island Biological Associa- 
tion, a field laboratory was maintained at Cold 
Spring Harbor where experiments and test 
work requiring magnetic quiet were carried 
out. The laboratory acquired an experimental 
airplane, a Grumman G-21A (twin-engined 
amphibian), in September 1942, which was 
housed in a Navy hangar at Roosevelt Field. 
Two protected rooms provided adequate space 
for flight equipment and plane supplies in this 
hangar. The total floor space in the Mineola 
vicinity, including storage warehouses, was 
30,097 sq ft. 

Early in 1943, increased activities on the 
west coast made it necessary to provide labora- 
tory, office, and storage space for the men en- 
gaged in experimental and Service installa- 
tions in California. Through the cooperation 
of the Harlow Aircraft Company at Alhambra, 
a temporary frame building for laboratory and 
stock use together with suitable office space in 
a fireproof building were made available. 

In addition to the main and branch labora- 
tories at Mineola and Alhambra, certain facili- 


ties were provided at 19 Army and Navy bases. 

Laboratory Airplane . The bimotored Grum- 
man G-21A amphibian plane (Navy designa- 
tion JRF-5) which was urgently needed for 



Figure 23. Administration Buildings, Alhambra, 
California. 


magnetic airborne detection [MAD] research 
and installation activities was purchased in 
September 1942 following approval by the Joint 
Aircraft Committee. As delivered, it was 



Figure 24. Field Station, Tucson, Arizona. 


equipped with normal flight and navigation in- 
struments as well as standard Navy transmit- 
ting, receiving, and direction-finding radio 
equipment. Later, a lightweight commercial- 
type transmitter and receiver were installed for 
normal airway communications. The plane was 
powered by two 450-hp Pratt and Whitney 
Wasp Jr. engines and was operated at a maxi- 
mum weight of 8,500 lb. It had a useful load of 
2,500 lb and a cruising speed of 140 mph. The 




66 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


plane was painted the standard Navy two-tone 
blue and carried the CAA designation NX- 
1604. 

A 3,800-hour pilot and an experienced air- 
craft and engine mechanic were employed by 
the laboratory to assure satisfactory flight op- 
erations and maintenance. The plane was 



Figure 25. JRF — experimental plane. 

equipped with chest-type parachutes which are 
carried on certain types of test flights, and 
with C0 2 inflatable life preservers which were 
carried when the plane was used in overwater 
operations. 

The plane was normally based at Mineola, 
New York, where it was housed in hangar F 
of the Roosevelt Field Naval Air Facility. The 
various regulatory bodies (CAA, FCC, PAW, 
Fighter Commands, etc.) waived wartime 
flight restrictions to permit effective use of the 
plane as required in the work of the laboratory. 

Since its purchase, the plane served as a 
prototype for dual MAD installations and was 
used extensively in the test of MAD equipment 
and accessories. It was flown in experiments 
over submarines off San Diego, and over mag- 
netic loops at the Mojave Bombing Range and 
at Langley Field, Virginia. Its most frequent 
target for test work was the partially sub- 
merged hull of the torpedoed tanker “Gulf 
Trade” located about 3 miles off Barnegat 
Light, New Jersey. The plane was used fre- 
quently to ferry engineers and MAD equipment 
from the laboratory to Langley Field, Virginia, 
and Quonset Point Naval Air Station, Rhode 
Island, when tight installation schedules were 
tied in with the departure dates of operating 
Service squadrons. 


By July 14th, the plane had accumulated a 
total of 439 air hours and at that time it was 
laid up for complete overhaul. It was returned 
to service on August 25th after the addition of 
a new AN/ASQ-2 installation and an inde- 
pendent 24-volt d-c, 50-ampere capacity auxili- 
ary power supply. 

The availability of an experimental plane has 
been of great value to the laboratory since it 
has expedited the working out of MAD instal- 
lation and compensation techniques aboard air- 




Figure 26. Loop, Langley Field, Virginia. 


craft and has provided means for quickly ob- 
taining information as to the performance of 
equipment in flight. Satisfactory design of air- 
borne electronic equipment is highly dependent 
upon such flight tests. In this connection it may 
be of interest to note that members of the lab- 
oratory staff flew a total of 6,335 hours in the 
12-month period ending August 31, 1943. 

Personnel 

The original group on this project consisted 
of Dr. L. B. Slichter, who initiated the work; 
Dr. J. N. Adkins; Dr. N. A. Haskell; Judson 
Mead; and C. S. Pearsall. Dr. D. G. C. Hare 
joined this group in August of 1941. In addi- 
tion to this group at Quonset Point, several 
groups were working on various phases of this 
problem elsewhere. Among these may be men- 
tioned V. V. Vacquier and L. D. Palmer at the 
Gulf Research and Development Corporation; 




FACILITIES ORGANIZED UNDER DIVISION 6 


67 


W. J. Shackleton, E. P. Felch, and T. Slonczew- 
ski at the Bell Telephone Laboratories; A. W. 
Hull and others at the General Electric Com- 
pany ; and R. T. Knapp and M. Serrurier at the 
California Institute of Technology. In Novem- 
ber of 1941 eight additional people were added 
to the staff at Quonset Point and in January of 
1942 the staff there totaled about 25. A large 
number of men was added in March and April 
and the total at the end of the first year was 
about 80. The total staff on this work grew to 
160 by the end of 1942 and to over 350 by the 
end of 1943. 

Research and Development 

As mentioned, the problem was that of de- 
tecting submerged submarines from aircraft. 
The most promising method seemed to be that 
of measuring the distortion in the magnetic 
field of the earth caused by the presence of the 
ferromagnetic mass of the submarine. The 
magnetic field of the earth has a total intensity 
of about 60,000 gammas (1 gamma equals 10 -5 
gauss), and the distortion of this field due to 
the presence of a submarine at a distance of a 
few hundred feet is of the order of 1 to 10 
gammas. Since the problem deals with a vector 
field, any relative motion between the sensitive 
axis of the measuring device and the direction 
of the field must be either neutralized or such 
motion must be eliminated by stabilization. At 
the start of this work, devices capable of meas- 
uring a few microgauss were available and, 
therefore, the major portion of the effort of this 
program was to eliminate the effect of those 
motions of the aircraft relative to the magnetic 
field which might give rise to spurious signals 
in the equipment. 

The British System. The division’s work on 
the problem of magnetic detection of subma- 
rines from aircraft began in the spring of 
1941 when Dr. J. T. Tate, then Chief of Sec- 
tion C-4, and Dr. L. B. Slichter conferred in 
England with those of the British interested in 
this work. The British had developed a two- 
coil gradiometer system with which it had been 
possible, under favorable conditions, to detect 
a submarine at the range of 200 ft. The British 
expressed the opinion that this range was too 
small to be of operational value but that, if the 


range could be doubled, an instrument of great 
value would be available. The British equip- 
ment consisted of two large coils about a foot 
in diameter, mounted coaxially in a rigid 
framework and separated by about 8 ft. Each 
coil, which was as far as possible identical to 
its mate, was wound with a large number of 
turns of wire such that the product of its area 
in square centimeters and the number of turns 
was about 10 8 to UP. These coils were connected 
in opposition, thus forming a gradiometer. 
Magnetically, a submarine is very nearly equiv- 
alent to a magnetic dipole. The magnitude of 
such a field varies with the inverse third power 
of the distance from the dipole. An airplane 
carrying a balanced coil system will measure 
the space change of the gradient which varies 
with the inverse fifth power of the distance. 
Thus, to achieve the result desired by the Brit- 
ish necessitated an increase of the usable sen- 
sitivity by a factor of 32. Since measurements 
of this sort are nearly always limited by the 
background noise present, this requirement ef- 
fectively calls for a reduction in the noise level 
by the same factor. 

Early investigations indicated that a large 
portion of the background noise was due to de- 
flections of the coil mounts and, therefore, the 
first phase of this work was to devise a coil 
mounting sufficiently rigid to keep the electrical 
axes of the coils parallel to within extremely 
close limits. Work was begun independently at 
BTL and the California Institute of Technology 
on the design of suitable coil mountings and, 
in addition, amplifiers were constructed by 
BTL and others which were capable of amplify- 
ing the very small low-frequency voltage to be 
expected. Work on this project was continued 
until November 1941, at which time it was ter- 
minated in view of the satisfactory tests of the 
Vacquier equipment. 

Vctcquier Magnetic Detector Mark I. This 
equipment was developed as the result of work 
begun in November of 1940 by the Gulf Re- 
search and Development Company. In the form 
as tested at Quonset, it consisted of a saturated- 
core mu-metal magnetometer mounted on a 
gravity-erected gyroscope which stabilized it 
about the vertical. The system was held in azi- 
muth by a servo motor which was controlled by 


68 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


the output of a second mu-metal magnetometer. 

This equipment was tested in November of 
1941 at Quonset Point and the flight test made 
at that time showed that signals could be ob- 
tained from S-type submarines at altitudes of 
more than 400 ft. The equipment, when 
mounted in the hull of a PBY airplane, had a 
noise level in a straight and level flight of ap- 
proximately 3 gammas. Its inherent noise level 
on the ground in a quiet location was about 0.2 
gamma. This was the first device which showed 
promise of being operationally usable as the 
detector of submerged submarines from air- 
craft. Further tests made in conjunction with 
our own submarines indicated that, contrary 
to earlier considerations, it was necessary that 
the equipment function at all times during 
flight, including the period in which the air- 
craft was making rapid maneuvers. For several 
reasons, the noise level on the Vacquier equip- 
ment was unreasonably high when the airplane 
was maneuvering. The primary cause of this 
high background was that the gyroscope, being 
gravity-erected, would precess off the vertical 
as a result of the centrifugal force during a 
turn and would thus give rise to a large anoma- 
lous signal when coming out of a turn. Con- 
tributing causes to the background were the 
local fields due to the aircraft’s ferromagnetic 
as well as conducting parts. These disturbing 
fields arise when there is relative motion with 
respect to the magnetic field of the earth. Dur- 
ing the weeks following the first successful test 
of this equipment, efforts were made to reduce 
these sources of noise. It was soon realized that 
little could be done about the inherent limita- 
tion of the gyroscope. Considerable improve- 
ment was made in the residual noise due to the 
aircraft’s structure by deperming hard steel 
members and compensating for the effects of 
others. 

Other Methods of Stabilization. With the 
recognition of the limits of the gravity-erected 
gyroscope, work was immediately started inde- 
pendently on three alternative methods of sta- 
bilization. A group under A. W. Hull at the 
General Electric Company began development 
of the gyroscope which would be erected along 
the earth’s magnetic field and for which the di- 
rection of the axis of erection would be inde- 


pendent of acceleration. It was suggested, ap- 
parently simultaneously and independently by 
several workers, that a system could be devised 
which would measure the magnitude of a vec- 
tor field without reference to its direction. In 
general, these schemes involve mounting three 
measuring devices in an orthogonal system, 
thus measuring three mutually perpendicular 
components of the vector field. Since the magni- 
tude is proportional to the square of the sum 
of these components, by squaring and adding 
the outputs of the three detectors, it is possible 
to measure the magnitude of the field only. The 
possibility of squaring and adding three cur- 
rents or voltages to the necessary precision was 
the subject of active investigation by the group 
at Quonset Point and at the Bell Telephone Lab- 
oratories. 

During November 1941, it was proposed that 
it would be possible to orient the detecting ele- 
ment along the magnetic field by means of two 
independent magnetometers mounted perpen- 
dicular to each other and to the detecting ele- 
ment in a set of gimbal axes. The output of 
these orienting magnetometers controlled ser- 
vo motors which kept them at all times per- 
pendicular to the magnetic field of the earth. The 
detecting element was thus held along the field. 

Early in December, it was decided that the 
majority of the effort on this project should be 
centered on this latter method. Accordingly, in- 
dependent developments were started at Quon- 
set Point, at BTL, and at Gulf Research and 
Development Company. The equipment desig- 
nated as Mark IV MAD was first flight-tested 
on February 15, 1942, and successful tests were 
made early in March by the group at Quonset 
Point. 

Work on the magnetically erected gyroscope 
was continued by the group under Hull at Gen- 
eral Electric and later by Vacquier working at 
the Sperry Laboratories in Garden City under 
an arrangement made by this laboratory. In 
April of 1942, BTL, realizing that the early 
servo systems used for orienting the magne- 
tometers were perhaps unsatisfactory, began 
the development of a system which used the 
magnetic method of orientation but, in addi- 
tion, squared the outputs of the three magne- 
tometers and added them as a correction fac- 


FACILITIES ORGANIZED UNDER DIVISION 6 


69 


tor to eliminate servo failure. This work was 
satisfactorily continued although later develop- 
ments of the servo system indicated that noth- 
ing could be gained by the square law compen- 
sation. Work on the magnetically erected gyro- 
scope was concluded after successful flight tests 
in the summer of 1942. At that time, the mag- 
netically stabilized system had been developed 
to a point such that the errors due to servo 
failure were entirely negligible in comparison 
to the other background noise. 

Noise Elimination. The development of a 
streamlined housing which would contain the 
equipment and which could be towed some dis- 
tance from the airplane was begun as a part of 
the two-coil program in the summer of 1941, 
and was continued throughout the year. Dur- 
ing April and May a reasonably satisfactory 
housing was developed by Knapp of the Cali- 
fornia Institute of Technology and was flight- 
tested at Quonset Point. At about the same 
time, a tail cone mounting in which the equip- 
ment was mounted in a nonmetallic housing 
which was an extension of the fuselage, was 
developed to enable the equipment to be used in 
an Army B-18. Both of these methods allowed 
considerable reduction in background noise and 
general development work in this field was con- 
tinued throughout the contract. 

In November of 1941, a definite program was 
begun with the objective of developing tech- 
niques for the compensation of anomalous mag- 
netic fields produced by the aircraft. During 
the spring of 1942 this work had progressed to 
a point where maneuver noise was reduced in 
many cases by factors of 10 to 1. Techniques 
were developed for the compensation of effects 
due to permanent and induced magnetization 
of the airplane’s structural members and pre- 
liminary work was begun on the reduction of 
noise due to eddy currents generated in the 
conducting members near the detecting ele- 
ment. This general work was perhaps one of 
the most important and fruitful projects of the 
contract period. 

Use on Surface Craft. A test installation of 
a Mark IV unit was made on a PC boat at the 
request of the Navy and trial runs indicated 
that satisfactory operation shielding ranges of 
from 800 to 400 ft might be obtained with ade- 


quate compensation. In view of other develop- 
ments by the Naval Ordnance Laboratory for 
this purpose, this project was not continued. 

Summary of Activities 

Chronologically, the outstanding develop- 
ments in MAD equipment were as follows. 

Mark IV-B2 MAD — July 191+2. This was an 
improved production-model magnetic airborne 
detector designed by Airborne Instruments 
Laboratory. 

Studies of Magnetic Fields above Submarines 
— September 191+2. A large number of measure- 
ments of the static magnetic fields above sub- 
marines have been made. On the basis of this 
information, dynamic signals have been com- 
puted and checked by model measurements. 
This information is of great value in the de- 
velopment of tactics and in the evaluation of 
bombing probabilities. 

Attack Trainer — October 191+2. The magnetic 
attack trainer [MAT] is a device developed to 
allow practice on various suggested MAD tac- 
tics. Its function is twofold: (1) to evaluate 
suggested MAD tactics, and (2) to train Serv- 
ice personnel (pilots) in the use of MAD, fol- 
lowing approved tactics. 

Mark VI MAD — December 191+2. (Army- 
Navy Designation — AN/ASQ-1 — AN/ASQ- 
1A). This is a lightweight version of the Mark 
IV-B2 and incorporates increased sensitivity 
and stability. It entirely superseded Mark IV- 
B2 from the production standpoint. Identified 
originally by the laboratory designation Mark 
VI, this equipment is now coded under the 
standard Army-Navy method of nomenclature 
as AN/ASQ-1 (when used with earlier polar 
head) and AN/ASQ-1 A (when used with the 
new universal head). 

Automatic Release Mechanism — January 
191+3 (Army-Navy Designation — CP-2/ASQ-1). 
This apparatus is designed to identify, for 
the purpose of automatic flare and bomb re- 
lease, the peak of the MAD signal obtained 
from a submarine. 

The Universal Head — January 191+3 (Army- 
Navy Designation — DT/3/ASQ-1A) . This is 
an improvement on the earlier magnetically 
oriented detector mounting and offers the very 
great advantage of permitting operation with- 


70 


ORGANIZATION OF THE SUBSURFACE WARFARE GROUP 


out mechanical change in any magnetic lati- 
tude. 

MABS — February 19J+3 (Army-Navy Desig- 
nation — AN/ASQ-2 — AN / ASQ-2A ) . The mag- 
netic airborne bombsight [MABS] is equip- 
ment designed to determine the lateral position 
of the submarine with respect to the airplane 
at the time the magnetic signal is received so 
that bombs will be automatically released only 
if the plane is within effective barrage range. 
A visual Indicator shows whether the subma- 
rine is to the left or right of the plane. MABS 
is now coded AN/ASQ-2 or AN/ASQ-2A 
(polar or universal heads). 

Compensation — March 19J>3. This refers to 
the development of techniques for compensat- 
ing the disturbing magnetic effects of the air- 
plane on the detector. These techniques have 
been developed to a very high degree and, at 
the present time, permit satisfactory compen- 
sation of the permanent, induced, and eddy cur- 
rent magnetic effects of all airplanes which 
have been suggested as MAD carriers. 

Each of the developments mentioned above is 
described in greater detail in another volume of 
this report. 

Other Laboratories 

The preceding sections of this chapter have 
been concerned with the laboratories or groups 
especially and specifically established to carry 
out the work of Division 6. It is not implied 
that all the research and development work in 
the field of subsurface warfare or even all of 
the work of Division 6 was carried on by these 
organizations. The Navy had large programs 
at the Naval Research Laboratory, at the Naval 
Ordnance Laboratory, and under contracts with 
civilian agencies. In fact, almost all of the 
progress in the art of locating submarines by 
supersonic methods that was made during the 
period between the end of World War I and the 
beginning of World War II was due to the 
Naval Research Laboratory operating on a 
very limited peacetime budget. As soon as 
World War II appeared imminent, the program 
of the Naval Research Laboratory, as well as 
those of other groups under the Bureau of 
Ships, was greatly increased. 


Likewise considerable work relating to sub- 
surface warfare was carried on by other divi- 
sions of NDRC. Division 3, for instance, car- 
ried on many important ordnance developments 
making use of rockets. The Radiation Labora- 
tory developed radar to detect surfaced sub- 
marines at night and in fog. Several months 
(October 1, 1940) before Section C-4 was 
started, a contract had been negotiated with the 
Woods Hole Oceanographic Institution under 
the directorship of C. O’D. Iselin to study the 
transmission of sound in the ocean. This work 
was so intimately related to the fundamental 
research undertaken by Section C-4 and later 
Division 6 that the Woods Hole contract was 
placed under the general supervision of this 
division. The Woods Hole Institution made a 
very large contribution in manpower, labora- 
tory space, and ship facilities to the program 
of the division. 

The existing industrial research laboratories 
also made a large contribution to the work of 
the division. Because of its very great experi- 
ence in the air-acoustic field, the staff of BTL 
was of invaluable help in setting up a pro- 
gram. Several large contracts were let with the 
Western Electric Company, Inc., under which 
research and development were done by BTL. 
These included work on the development and 
construction of primary and secondary stand- 
ard underwater acoustical receivers and pro- 
jectors, the design of a supersonic prism for 
underwater scanning, the investigation and 
development of equipment for locating sub- 
marines by magnetic methods, the investigation 
and development of listening systems and har- 
bor-protection devices, the development of spe- 
cial types of torpedoes, and for the development 
of special batteries for electrically driven tor- 
pedoes. 

Likewise several contracts were let with the 
General Electric Company. These covered the 
detection of submarines by magnetic methods, 
by light pulsing and by special acoustical meth- 
ods, and the development of special types of 
torpedoes. Other contracts concerned with the 
development of special torpedoes were with the 
American Can Company, Westinghouse Elec- 
tric Corp., Newark College of Engineering, 
Electrical Engineering and Mfg. Corp., and the 




FACILITIES ORGANIZED UNDER DIVISION 6 


71 


Leeds and Northrup Co. In connection with the 
detection of submarines by magnetic methods, 
contracts were drawn up with the Gulf Re- 
search and Development Co. and the Goodyear 
Aircraft Corporation. Extensive equipment 
was set up at the California Institute of Tech- 
nology for the study of underwater trajectories 
of bombs and torpedoes and for the study of 
cavitation and other phenomena utilizing a 
high-speed water tunnel. Additional work of 
this same character was carried on at the Iowa 
Institute of Hydraulic Research of the Univer- 
sity of Iowa. Other contracts covering particu- 
lar projects were let with the Massachusetts 
Institute of Technology, Armour Research 


Foundation, Radio Corporation of America, 
and the Sangamo Electric Company. 

The important part that these various in- 
dustrial and academic contractors played in 
carrying out the work of Division 6 will be 
apparent in the technical descriptions of their 
contributions in other volumes of this report. 

Conspicuously omitted in this chapter on the 
organization of the Subsurface Warfare Group 
are discussions of the divisional units dealing 
with Operational Research, Selection and 
Training, and Field Engineering. This is be- 
cause these three branches of the work of Di- 
vision 6 are described in later chapters in 
greater detail than would be possible here. 


SECR 



PART II 


OPERATIONS RESEARCH 












Chapter 4 

THE ROLE OF OPERATIONS RESEARCH IN ANTISUBMARINE WARFARE 

By Philip M. Morse 


A s Division 6 got under way, the vista of pos- 
_ sibilities for technical assistance to the 
Navy widened rapidly. 

Scientific help has been useful in the design of 
engines of war since the time of Archimedes. 
But until comparatively recently the resulting 
devices were simple enough so that the details 
of tactics and strategy could be left to the non- 
scientific military staff. In modern war, how- 
ever, the equipment in use is so complicated 
that a scientific investigation of various tactics 
utilizing all available mathematical and sta- 
tistical techniques can result in large improve- 
ments in operational effectiveness. This is par- 
ticularly true of antisubmarine operations, the 
effectiveness of which depends upon the prop- 
erly integrated use of an array of extremely 
complex gear. It is not surprising, therefore, 
that the first operational research group organ- 
ized in the United States was in this field. 

As has been pointed out, the first responsi- 
bility of Division 6 was in the direction of im- 
proving the design of underwater sound equip- 
ment for the detection of submerged subma- 
rines. As the field of activities of the division 
expanded, it soon became apparent that effec- 
tive assistance could be provided only if the 
scope of the division’s studies was widened to 
include all the gear taking part in the attack 
by a surface vessel on a submarine. In order 
to evaluate the relative importance of the mul- 
titude of problems which presented themselves, 
it was necessary to study the tactics of the at- 
tack. As the scope of the investigation thus 
widened, some of the theoretical aspects seemed 
to be of interest to those in the Navy directly 
concerned with operations against the sub- 
marine, that is, the actual users of the equip- 
ment. 

Thus by a natural development completely 
analogous to the earlier development in Eng- 
land, scientific aid in antisubmarine warfare 
began by assisting in the design and production 
of equipment and finally was extended to the 


assisting in the planning of operations using 
the equipment. This extension of scientific aid 
into the realm of operations called Operations 
Research or Operational Analysis, is an innova- 
tion of World War II. 

41 ANTISUBMARINE WARFARE IN 
WORLD WAR II 

Period III— April 1941 to 
December 1941 

April 1941, when Division 6 of NDRC was 
just getting under way, marked the beginning 
of the U-boat war’s third period, which was to 
last until December 1941. 

It has been shown how Allied countermeas- 
ures forced the Germans to abandon the tactics 
with which they had commenced operations, by 
attacking in daylight at periscope depth, in 
favor of night attacks on the surface. Period 
III was to see U-boat commanders once again 
forced to modify their attack procedures, due 
in no small part to the equipment which science 
had placed in the hands of the antisubmarine 
forces. The effectiveness of Allied escort ves- 
sels equipped with the high-frequency direction 
finders and radar was making the close surface 
night attack by one or two U-boats increasingly 
hazardous. The German answer was adoption 
of the wolf-pack system of attack. In this sys- 
tem, a U-boat encountering a convoy withheld 
its attack until it could summon other sub- 
marines in the vicinity for an attack in unison. 

An additional reason for the adoption of the 
wolf-pack system was that because of deaths 
due to Allied action and the expansion of the 
U-boat fleet, seasoned submarine officers and 
men were being spread thinner and thinner. 
The wolf-pack attack in concert enabled less 
experienced U-boat crews to be guided by their 
more experienced colleagues. 

April 1941 saw the enemy extending the 


75 


76 


OPERATIONS RESEARCH IN ANTISUBMARINE WARFARE 


areas of submarine attacks south and west. Of 
the 41 merchant ships of 240,000 gross tons 
sunk by U-boats in April, nearly 30 per cent 
were sunk in the Azores and the Freetown 
areas. In May 1941 sinkings by U-boats 
mounted to 58 ships of 325,000 gross tons, more 
than half of the loss being in the Freetown 
area. By June of 1941 U-boats were raiding 
as far away as Newfoundland and south of 
Greenland. Losses to U-boats for the month 
were 57 ships of 296,000 gross tons. On the 
other side of the ledger, however, 5 U-boats 
were sunk. 

In the face of these sinkings it became clear 
to the Allies that the only means of safeguard- 
ing shipping was to provide an escort clear 
across the Atlantic even though this meant 
spreading the limited number of available es- 
cort vessels even thinner. In July 1941, Presi- 
dent Roosevelt announced that the safety of 
the United States required the basing of Amer- 
ican antisubmarine forces in Iceland. 

During July, August, and September 1941, 
100 merchant vessels fell victims to the sub- 
marine. They had a total tonnage of 385,000 
gross tons. 

September 1941 was marked by the declara- 
tion by the United States that it would protect 
all ships carrying lend-lease materials regard- 
less of the ship’s nationality. On September 16 
convoy HX-150 sailed from Halifax with war- 
ships of the United States Navy appearing for 
the first time among the escort vessels. 

In October 1941, the United States Navy suf- 
fered its first casualties as the result of U-boat 
action. USS Reuben James was torpedoed and 
sunk. USS Kearney was torpedoed but suc- 
ceeded in making port in Iceland. Shipping 
losses for the month of October totaled 32 ves- 
sels of 137,000 gross tons. 

Only 12 ships of 62,000 gross tons were sunk 
by U-boats during November 1941. This com- 
paratively low rate of sinkings could be at- 
tributed in part to the fact that the British 
offensive in Libya was causing the Germans to 
divert some of their submarines in the Atlantic 
to the Mediterranean. But an important con- 
tributing factor was the work of the British 
Coastal Command whose aircraft made the 
U-boat commanders prefer to stay outside their 


patrol range of some 400 miles offshore. Ex- 
perience in the evasive routing of convoys was 
also having its effect. 

Between December 7, when the United States 
was thrust into the war by the Japanese attack 
on Pearl Harbor, and the end of the month, 
Japanese submarines sank nine Allied vessels 
of 42,000 gross tons. During December, 10 
ships of 50,000 gross tons were sunk in the 
Atlantic and 7 ships of 27,000 gross tons were 
sunk in the Mediterranean. The Allies, how- 
ever, were making the enemy pay for his suc- 
cesses. Five U-boats were sunk in the Medi- 
terranean and in one attack by six U-boats on 
an Atlantic convoy, four of the attacking sub- 
marines were sunk, though at the loss of mer- 
chant ships, one escort vessel and HMS Au- 
dacity, the first British escort carrier. 

The third phase of the antisubmarine war 
was marked by a number of technical innova- 
tions. 

CAM ships, merchant vessels equipped with 
fighter aircraft launched from catapults, were 
introduced. An analysis of attacks on sub- 
marines by aircraft showed that in at least one- 
half of them the aircraft dropped the depth 
charges while the U-boat was still visible or had 
submerged less than 30 seconds before. This 
led to a change in the depth setting for all depth 
charges to 50 ft and later to 25 ft. 

During this phase of the war, the British 
adopted the hedgehog, a multiple spigot mortar 
mounted on the forepart of an escort ship 
which could forward-fire a pattern of bombs 
armed to explode on contact. Aircraft patrols 
over the Bay of Biscay were intensified and 
had the effect of forcing U-boats to run sub- 
merged in their transit to and from the French 
ports, thus increasing their transit time and 
correspondingly decreasing the time they could 
remain at sea. 

The British during Period III made several 
notable advances in the use of radar. The short- 
wave 10-cm radar device was developed and 
fitted on British corvettes. 

During the period a total of 44 enemy sub- 
marines were sunk, 22 German and 8 Italian 
submarines in the Atlantic, 6 German and 7 
Italian submarines in the Mediterranean and 
one Japanese submarine in the Pacific. 




ANTISUBMARINE WARFARE IN WORLD WAR II 


77 


These losses, however, were more than being 
offset by the new U-boats coming off the ways 
as the result of the intensified construction pro- 
gram. At the start of the period, the Germans 
had approximately 54 U-boats available and 
were able to keep about 18 at sea in the At- 
lantic at all times. At the close of the third 
phase of the war, the number of available 
U-boats had risen to approximately 200 and the 
average number in the Atlantic at any one time 
was about 36. 

This great expansion of the U-boat fleet, 
however, had its effect in a telling loss of effi- 
ciency. The larger number of U-boats at sea 
were able to sink only about 34 ships of 166,000 
gross tons per month in the Atlantic during 
Period III, or about 25 per cent less than dur- 
ing the previous period. This meant that the 
average U-boat was sinking only one ship of 
about 5,000 gross tons per month at sea and 
was therefore only about one-fourth as effective 
as in the previous period. 

During the antisubmarine war, third phase, 
the British were able to increase the number of 
escort vessels from 375 to approximately 500 
and the entry of the United States into the war 
added 175 destroyers to the number of available 
escorts. 

There was some improvement in the Allies’ 
shipping position. Losses averaged 363,000 
gross tons per month as against 175,000 gross 
tons of new construction making a net loss of 
188,000 gross tons per month, which was 45 
per cent less than during the previous period. 
Despite this hopeful sign, total net losses for 
the period brought shipping available to the 
Allies down to 33,000,000 gross tons at the 
period’s close. 


Period IV — January 1942 to 
September 1942 

Period IV of the antisubmarine war found 
the U-boats extending their range to the very 
shores of the latest principal participant, the 
United States. 

The crisis in the U-boat war came during the 
first 6 months of 1942. By this time the Ger- 
mans had about 200 ocean-going submarines, 


and new ones were being commissioned at the 
rate of about 20 a month; thus it was possible 
for the Germans to maintain a large-scale 
U-boat offensive over widely spread areas. The 
average number of U-boats at sea in the At- 
lantic increased steadily from 22 in January 
1942 to 93 in September 1942. The relatively 
unprotected coastal shipping along the Amer- 
ican seaboard was their target. Transatlantic 
convoys had been getting rather expensive to 
attack, as has been mentioned in the first chap- 
ter of this volume. In December 1941, for in- 
stance, 4 U-boats had been sunk in an attack 
on one convoy where only 2 merchant ships 
were sunk. It was natural that the submarines 
would turn their efforts toward a less well-pro- 
tected prey. 

The United States, with their antisubmarine 
forces reduced by the destroyers turned over 
to the British, by their commitments in trans- 
atlantic escort, and by the demands of the war 
in the Pacific, were caught unprepared for the 
scale of attack launched by the U-boats on the 
Atlantic coast in 1942. The forces available to 
combat these enemy activities were relatively 
untrained and inexperienced. With a limited 
number of antisubmarine craft, both surface 
and air, at their disposal, the U. S. Navy was 
unable to start convoying of coastal shipping 
immediately, but tried during the early months 
of 1942 to cover this long coastal route by pa- 
trol. This produced a number of attacks on 
U-boats, but it failed to prevent extremely 
heavy losses of shipping which were sailing un- 
escorted along the coast. 

Submarine activity in the west Atlantic 
began on January 12, 1942, when the first sink- 
ing in the U. S. strategic area occurred. A force 
of about 20 U-boats began to operate off the 
Atlantic seaboard of the United States, picking 
off tankers and larger cargo ships by preference 
and avoiding convoys. As long as worth-while 
targets abounded in the form of unarmed and 
unescorted ships, the U-boats kept clear of the 
escorts. 

These submarines inflicted their heaviest 
losses in January in the eastern sea frontier, 
along the eastern coast of the United States, 
sinking 14 ships of about 100,000 gross tons. 
A large proportion of these losses occurred at 


78 


OPERATIONS RESEARCH IN ANTISUBMARINE WARFARE 


focal points of shipping such as Cape Hatteras 
and Hampton Roads. About 50,000 gross tons 
of shipping were sunk by U-boats in the north- 
west Atlantic, Canadian coastal, and Bermuda 
areas. There was comparatively little activity 
in the remainder of the Atlantic. The total 
losses for the month, 61 ships of 324,000 gross 
tons, were higher than those in any month of 
the previous period. 

The situation became much worse in Febru- 
ary 1942 when the world-wide shipping losses 
to U-boats reached a new high for the war with 
82 ships of 470,000 gross tons being sunk by 
submarines. This loss was considerably greater 
than the rate at which we were replacing ship- 
ping. About 90 per cent of the losses occurred 
in the U. S. strategic area. As the number of 
U-boats operating in the west Atlantic in- 
creased and U-boat activities spread further 
south to Florida and the Caribbean Sea, tanker 
losses continued to be severe. Tanker traffic to 
and from the West Indian and Venezuelan oil 
fields was an obvious objective of the U-boats. 

During March the U-boats continued their 
same tactics with increased success, sinking 
94 ships of 530,000 gross tons. The most active 
area continued to be in the eastern sea fron- 
tier with over 150,000 gross tons of shipping 
being sunk there by U-boats. The one encour- 
aging feature of the month’s operations were 
the first successful attacks on U-boats in the 
U. S. strategic area. Two U-boats were prob- 
ably sunk in March as a result of attacks by 
U. S. Navy aircraft in the northern part of 
the area. On the fifteenth of April, USS Roper 
sank U-85 off Cape Hatteras, picking up 29 
bodies, for the first confirmed sinking of a 
U-boat off the U. S. coast. The number of at- 
tacks on U-boats in the U. S. strategic area had 
increased from about 15 in January to about 
60 in April. 

The increase in the counterattack probably 
played some part in causing a small decrease 
in shipping losses in April, but a more impor- 
tant factor was the temporary suspension of 
sailing in certain areas. U-boat activity spread 
to the Brazilian area during April. 

In the middle of May 1942, the U. S. Navy 
was able to provide convoys for shipping along 
the east coast. The effect of the institution of 


these convoys was immediately apparent. The 
U-boats avoided escorted shipping, and the 
tonnage sunk by U-boats in the eastern sea 
frontier in May dropped to a mere 23,000 gross 
tons. The U-boats, however, simply sought out 
the remaining soft spots where unescorted traf- 
fic had to pass through focal areas, and oper- 
ated actively off the mouth of the Mississippi 
and in the Yucatan channel between Cuba and 
Nicaragua. Though the average number of 
U-boats at sea in the Gulf sea frontier in May 
1942 was only about four, these U-boats sank 
41 ships of 220,000 gross tons there during the 
month, an all-time high for sinkings by U-boats 
in any area. The average number of ships at 
sea in the Gulf sea frontier was about 75, so 
the average life of a ship at sea was less than 
two months at that rate of sinkings. 

It was, of course, realized that the only solu- 
tion to the heavy losses off the Atlantic coast 
during the early months of 1942 was the insti- 
tution of convoying of the coastal shipping. 
However, the U. S. Navy, because of its com- 
mitments in transatlantic escort and in the 
Pacific, did not have enough escorts to start 
the convoying. To provide additional forces, 
British antisubmarine trawlers were allocated 
for service on the American coast, and a few 
British corvettes were turned over to the U. S. 
Navy. Further, the whole system of trans- 
atlantic escort was recast, and all antisubma- 
rine forces, U. S., Canadian, and British, were 
pooled in a single cross-Atlantic convoy scheme. 
This resulted in some economy and released a 
limited number of U. S. destroyers. 

With the forces thus available and with the 
increased production of antisubmarine ships in 
the United States, it was possible to start con- 
voying in the western Atlantic in May 1942. 
This convoy system was gradually extended 
into the Gulf, the Caribbean, and finally down 
the coast of South America as more and more 
vessels became available. 

The effect of convoying in reducing shipping 
losses is clearly illustrated by the experience in 
the U. S. strategic area during the first nine 
months of 1942. There were about 600 ships 
on the average at sea in this area throughout 
this period. During the first six months before 
extensive convoying of coastal shipping was 


ANTISUBMARINE ORGANIZATION IN U. S. NAVY 


79 


started, only about 40 per cent of the shipping 
was in convoy. There were on the average about 
30 U-boats at sea in this area during the first 
six months, and each U-boat was sinking about 
2.7 ships a month. About 20 per cent of the 
independent shipping, and about 4 per cent of 
the convoyed shipping was sunk each month 
by U-boats. 

During the next three months after exten- 
sive convoying of coastal shipping had started, 
about 80 per cent of the shipping was in con- 
voy. The average number of U-boats at sea in 
this area had increased to about 50, but each 
U-boat was able to sink only about 1.4 ships a 
month, about half as much as during the first 
six months. Thus, despite the fact that the loss 
rates for both independent and convoyed ship- 
ping had increased during the last six months 
of this period, the efficiency of the average 
U-boat in sinking ships was halved. This was 
due mainly to the fact that about 40 per cent 
of the shipping was exposed, during the latter 
three months, to the much lower loss rate ex- 
perienced by convoyed shipping instead of to 
the high loss rate experienced by independent 
shipping. Thus, convoying proved a very val- 
uable defense in the crisis, but it was still not 
enough. 

At the beginning of 1942 the U. S. Navy sent 
out all available planes and blimps to battle the 
U-boat along the coast. They were helped by 
the First Bomber Command, an Army Air 
Force contribution which was activated in De- 
cember 1941. In addition to the Army and 
Navy flying, there was also patrolling by the 
Civilian Air Patrol [CAP] mostly within a 
hundred miles from shore. The flying hours by 
U. S. Army and Navy aircraft in the eastern 
sea frontier increased from about 5,000 hours 
in January to a peak of about 25,000 in July 
1942. Similar increases came in the other fron- 
tiers, although at a somewhat later date. 

The U. S. aircraft made about 30 attacks a 
month on U-boats during this first six months 
of 1942, starting from about 12 a month dur- 
ing the first four months to about 45 a month 
during the next few months. About 20 per cent 
of these attacks resulted in some damage to 
the U-boat, while only about 2 per cent resulted 
in the sinking, or probable sinking, of a sub- 


marine. Thus there was a large margin for 
improvement in the use of aircraft against 
U-boats. 


42 ANTISUBMARINE ORGANIZATION 
IN U. S. ]$AVY 

The organization responsible for the antisub- 
marine effort of the United States was also 
somewhat complex at the start. 

The convoy and routing section of the 
COMINCH (Commander-in-Chief, U. S. Fleet) 
staff had the duty of organizing and routing 
all convoys from American ports to some mid- 
way point where the convoy control was taken 
over by the British. Destroyers for this task 
were taken from the Atlantic Fleet, and 
ComDesLant (Commander Destroyers Atlantic 
Fleet) was responsible for readying these de- 
stroyers, training their crews, and for devising 
antisubmarine tactics for the escorts. 

The protection of the coastal shipping was 
in the hands of the various sea frontiers, east- 
ern sea frontier taking the region from Maine 
to Florida, Gulf sea frontier taking the Gulf 
region, Panama sea frontier the Panama ap- 
proaches, and Caribbean sea frontier the north- 
ern portion of South America and the Antilles. 
These sea frontiers operated local patrol craft, 
and also naval aircraft supplied by ComAirLant 
(Commander Aircraft Atlantic Fleet) and 
Army land-based bombers from the First 
Bomber Command. These craft were used for 
general patrol work along the shipping lanes, 
and later were used to a considerable extent 
in escorting coastwise convoys when these con- 
voys became established. 

Intelligence concerning submarine move- 
ments could be obtained from sinking and 
sighting reports. These reports were turned in, 
through the sea frontiers, to the Operational 
Intelligence Division, COMINCH, where they 
were evaluated and analyzed, and a coordinated 
report sent back to the interested frontiers. 
Each frontier kept its own plot where shipping 
and estimated submarines were shown and 
from which patrol, convoying, and attack plans 
could be made. 

The lines of authority of these various com- 


80 


OPERATIONS RESEARCH IN ANTISUBMARINE WARFARE 


mands were of necessity somewhat vague at 
first. The scope of submarine warfare in the 
Atlantic exceeded that of any of the frontiers, 
and at times and in certain areas extended 
beyond the operating area of the Atlantic Fleet. 
For instance, when submarine warfare spread 
to the coast of Brazil, the Fourth Fleet, a 
separate entity, was called on to carry out 
antisubmarine activity. 

It was felt that the control of convoys and, 
probably, the decisions on tactics, training, and 
equipment should be centered in COMINCH, 
since this would assure uniformity. But such 
a centralization could not be achieved immedi- 
ately, and at first tactics and usages varied 
considerably from place to place. Some diffi- 
culty was also encountered in transferring air- 
craft and patrol craft from one frontier to 
another as enemy submarines shifted the loca- 
tion of their principal activities. 

43 NEED FOR STATISTICAL ANALYSIS 

It was soon apparent that the craft, person- 
nel, and equipment available, and soon to be 
available, would have to be used to their utmost 
capabilities in order to beat back the subma- 
rine. The attacking team, whether on a de- 
stroyer or in an airplane, would have to know 
how to use its detection gear and its ordnance 
to the limit of its collective ability in order to 
make a kill. New equipment was being devised 
by the naval laboratories and by NDRC, and 
tactics suitable for this new equipment would 


have to be devised. All attacks would have to 
be studied carefully in order to derive the ut- 
most from experience. 

In order to analyze past operations and in 
order to utilize their lessons in devising new 
tactics, the Atlantic Fleet in February 1942 
set up the Antisubmarine Warfare Unit, At- 
lantic Fleet, in Boston under Captain (now 
Rear Admiral) Wilder D. Baker. This unit was 
made up of officers acquainted with submarine 
operations, officers from destroyers, a Navy air 
officer, and an Army air officer. A tactical man- 
ual was begun, and analysis of antisubmarine 
operations was made the subject of a monthly 
bulletin. 

It soon became apparent to Captain Baker 
and others of his unit that advice from scien- 
tifically trained civilians would be useful to 
the Antisubmarine Warfare Unit. Much of the 
new antisubmarine equipment was relatively 
unfamiliar to most naval officers and advice 
was needed from time to time in interpreting 
operational results. Also it was believed that 
some of the modern mathematical techniques 
could profitably be used in studying the sta- 
tistics of past operations, in order to learn 
tactical lessons from them. Consequently a let- 
ter was sent from Captain Baker to the Navy 
Coordinator of Research, requesting the help 
of NDRC personnel in the study of antisubma- 
rine tactics. The request was transmitted to 
NDRC and as a result, Research Group M 
(or ASWORG, as it was alternately known) 
came into being. 


Chapter 5 

NDRC BACKGROUND 


T he early development of the NDRC anti- 
submarine effort has been discussed in the 
previous chapter. As was mentioned in that 
chapter, there was some doubt on the part of 
certain naval officers as to whether or not 
NDRC could contribute help rapidly enough to 
be of use in the emergency. Thus, requests for 
aid were at first restricted to the field of under- 
water detection. 

It was true that most of the personnel of the 
NDRC laboratories had to learn the art of anti- 
submarine warfare from the beginning. But it 
is surprising how rapidly several dozen of the 
best technical men of the country can learn a 
field, especially when they are spurred with a 
sense of urgency; for by the middle of 1941 
it was obvious that the antisubmarine problem 
was of vital importance. As the groups began 
to find their way about in this new subject, a 
number of possible improvements in under- 
water detection equipment was suggested, a 
few of which turned out to be useful. As the 
work progressed, however, it began to be ap- 
parent that underwater detection gear might 
not be the crux of the problem. 

The Naval Research Laboratory, it turned 
out, had done an excellent job in designing the 
U. S. underwater echo-ranging gear. Naturally 
a number of improvements were devised and 
are now included in the standard gear, but 
these improvements increased by only a slight 
percentage the chance of success in the final 
attack. The difficulty seemed to be that the rest 
of the antisubmarine gear had not been corre- 
spondingly improved. The ordnance (depth 
charges) had hardly changed at all; and equip- 
ment designed to help aircraft make submarine 
attacks was practically nonexistent. It seemed 
that confining the activities of Section C-4 to 
underwater detection failed to take many im- 
portant factors into account. 

51 STUDIES ON A/S ORDNANCE 

A series of important and illuminating studies 
by Doctors L. B. Slichter and S. S. Wilks em- 


phasized this fact. They seemed to indicate that 
with the best underwater detection system pos- 
sible (allowing for the refractive effect of 
temperature gradients in the water) only about 
1 attack out of 20 would be likely to succeed 
if the usual depth charges were dropped. This 
conclusion was tentative, since it was based on 
assumptions regarding the actual operational 
behavior of both submarine and destroyer. At 
the time of the study, these factors did not 
seem to be known in this country with sufficient 
accuracy to enable one to say whether the 
studies of Wilks and Slichter represented the 
true conditions or not. 


52 NEED FOR OPERATIONS 

STATISTICS 

In fact, it was becoming apparent that the 
Bureau of Ships, at least, did not know in any 
quantitative manner the operation character- 
istics of their antisubmarine craft and gear 
when used by the average crew in actual war- 
time conditions. This lack of quantitative 
knowledge was not the fault of the Bureau of 
Ships, for they did not seem to have access to 
quantitative analyses of operational results. In 
1941, of course, there were no U. S. results to 
analyze ; but even after several months of 1942 
had passed, such analyses were still not forth- 
coming, despite the fact that a number of our 
ships and aircraft had already attacked Ger- 
man submarines. 

Those in authority began to realize that no 
such detailed quantitative analyses of opera- 
tional experience were being made anywhere 
in the Navy. This was not surprising; for 
almost every person in the Navy with any op- 
erational experience in antisubmarine warfare 
had been hurriedly drafted to go out to sink 
submarines or to carry out other important 
executive tasks, and not to analyze operations. 
There was a shortage of experienced skippers, 
operators, and personnel in general. Personnel 
with adequate scientific background to analyze 


81 


82 


NDRC BACKGROUND 


reports when they came in were not available. 
The Atlantic Fleet ASW Unit, which was a 
central planning- unit at that time, did not have 
the time, nor did its members have the neces- 
sary specialized mathematical and scientific 
skill, to make technical analyses. 

Consequently when Dr. Tate, as head of Sec- 
tion C-4, NDRC, replied with a ready affirma- 
tive to the request of Captain Baker for the 
assignment of technical and statistical experts 
to analyze operational antisubmarine data, the 
prompt response created a feeling of consider- 
able relief. 

Nor was the feeling of satisfaction one-sided. 
In addition to the value which the Navy felt 
that such studies would have in devising tac- 
tics, there was a belief in NDRC that such 
analyses would assist in the development of 
antisubmarine gear better suited to meet oper- 
ational needs. 

Before Captain Baker’s request had come, 
Section C-4, as previously noted, had been ex- 
panded in scope to cover the whole of subsur- 
face warfare. The advantages of such an ar- 
rangement had already been felt in a number 
of promising developments being worked on at 
the laboratories. This same broadening of the 
scope of the section made it quite logical that 
it should assume the responsibilities of organ- 
izing a group of scientific consultants to the 
ASW Unit of the Navy. 


5 3 BRITISH EXPERIENCE WITH 
OPERATIONS RESEARCH 

The need for technical and scientific experts 
to advise at the operational level had been felt 
earlier in England. TRE (Telecommunications 
Research Establishment) had been developing 
and building coastal aircraft-warning radar 
sets. As these were established along the Brit- 
ish coast in 1940, considerable difficulty was 
encountered in coordinating the sets with the 
operations of the defending fighter aircraft and 
also with the antiaircraft batteries. A small 
group, headed by Professor P. M. S. Blackett, 
was organized by TRE to study the effective- 
ness of these sets in actual operation. They 
soon found that it was necessary to work closely 


with the operational commands of Fighter 
Command RAF and also with the Army Anti- 
Aircraft Command. It also became clear that 
this group could profitably study operational 
problems other than those involving early- 
warning radar. Then came the realization that 
if the group was to be effective in its broader 
scope, it needed to be attached to the interested 
Services rather than to a development labora- 
tory such as TRE. 

As a result, the Operational Research Section 
was set up for Fighter Command; and the 
Army Operational Research Group was also 
established which eventually was headed by 
Professor (now Brigadier General) B. Schon- 
land. After completing the organization of 
Fighter Command ORS, Professor Blackett to- 
gether with Professor E. J. Williams set up a 
corresponding Operational Research Section 
with Coastal Command (ORS/CC). This sec- 
tion, in 1941, started publishing the results of 
its studies of antisubmarine and antishipping 
operations. Shortly after the establishment of 
Coastal Command ORS, a section was set up 
in Bomber Command with Professor Dickens 
as the head. Later, other sections were set up 
in other divisions of RAF and in other operat- 
ing theaters. 


Operational Research in the 
Admiralty 

In the spring of 1942 Professor Blackett was 
asked to organize operational research in the 
British Admiralty. Initially he was simply des- 
ignated as “Chief Advisor on Operations Re- 
search” [CAOR] to the First Sea Lord of 
the Admiralty (who corresponds roughly to 
COMINCH). Other scientists were assigned to 
various divisions of Admiralty such as the 
Anti-U-boat Division and the Mine Warfare 
Division. These scientists reported directly to 
their division heads, usually senior naval offi- 
cers. They also consulted directly, however, 
with Professor Blackett as CAOR. Later, Oper- 
ational Research was made an official division 
of Admiralty with Professor Blackett as “Di- 
rector, Naval Operations Research” [DNOR]. 
Similar organizations were set up in other 


BRITISH EXPERIENCE WITH OPERATIONS RESEARCH 


83 


parts of the British Services, such as the Com- 
bined Operations and Air Coordination. 

These operational research groups have had 
varying degrees of success. In general, they 
have been quite useful and have performed 
scientific services which neither the officer per- 
sonnel nor the development laboratory person- 
nel were in a position to carry out. 

It seems to be generally agreed by now in 
England (as well as in the United States) that 
there is definite need for scientifically trained 
civilians to act as advisors to the Operational 
Control officers. It is felt that they should have 
close contact with the higher echelon officers 
and should have complete access to operational 
plans and records. The following excerpts from 
an article by Professor Blackett, discussing the 
utility of Operational Research, indicate the 
point of view of the acknowledged authority in 
this field in England. 

The object of having scientists in close touch with 
operations is to enable operational staffs to obtain 
scientific advice on those matters which are not handled 
by the service technical establishments. 

Operational staffs provide the scientists with the 
operational outlook and data. The scientists apply 
scientific methods of analysis to this data, and are 
thus able to give useful advice. 

The main field of their activity is clearly the analysis 
of actual operations, using as data the material to be 
found in an operation room, e.g., all signals, track 
charts, combat reports, meteorological information, etc. 

It will be noted that this data is not, and on secrecy 
grounds, cannot, in general, be made available to the 
technical establishments. Thus such scientific analysis, 
if done at all, must be done in or near operation rooms. 

The work of an Operational Research Section should 
be carried out at Command, Groups, Stations or 
Squadrons as circumstances dictate. 

Experience over many parts of our war efforts has 
shown that such analysis can be of the utmost value, 
and the lack of such analysis can be disastrous. Prob- 
ably the main reason why this is so, is that very many 
war operations involve considerations with which 
scientists are specially trained to compete, and in 
which serving officers are in general not trained. This 
is especially the case with all those aspects of operations 
into which probability considerations and the theory 
of errors enter. Serving Officers of the highest calibre 
are necessarily employed in important executive posts, 
and are, therefore, not available for detailed analytic 
work. 

The records of some war operation (e.g., air attacks 
on U-boats for the previous six months) is taken as 


the data. This is analyzed as quantitatively as possible, 
and the results achieved are “explained” in the scientific 
sense, i.e., brought into numerical relation with the 
operational facts and the known performance of the 
weapons used. When this has been done, consideration 
is given to possible modification of the tactics to im- 
prove the operational results. 

The first step — that of collecting the actual data — is 
by itself of enormous importance, for it is not uncom- 
mon for operational staffs to be unacquainted with what 
is actually being achieved. An Operational Research 
Section is not in general concerned with “hot news,” 
though they should be prepared to so concern them- 
selves if specifically requested to do so. 

A typical problem is as follows : — a weapon A is 
calculated by a service technical department to be 
50% more efficient than a weapon B. Actual operations 
over a given period show, say, 2 successes for A and 
4 for B. Does this prove that B is a better weapon 
than A? 

Such points arise continually and require the highest 
scientific judgment to resolve. In particular a grasp of 
fluctuation phenomena (i.e., Poisson’s Distribution) is 
required. 

The scientist, in considering an operational problem, 
very often comes to the conclusion that the common 
sense view is the correct one. But he can often back the 
view by numerical proof, and thus give added con- 
fidence in the tactics employed. 

Or when two alternative qualitative views, “A is 
best” “B is best” are in dispute, he can often resolve 
this numerically into some such statement as that “A 
is x% better than B in January and y°/o worse in June.” 

In fact, the scientist can encourage numerical think- 
ing on operational matters, and so can help avoid run- 
ning the war by gusts of emotion. 

Since new weapons and devices are inevitably put 
into service . relatively untested, the first few months 
of the use of a new device must be considered as an 
extension of its development trials. An O.R.S. can 
function usefully here in a liaison capacity between the 
operational staff, the technical department which pro- 
duced the device, and the development unit which 
tested it. 

Further, it is often possible by collaboration between 
Controllers and the staff of an O.R.S. , to arrange 
operations on certain occasions so as to obtain data to 
clarify some doubtful point. For instance, the relative 
merits of different forms of A/S sweeps by aircraft is 
a matter of (a) mathematical calculation, (b) test by 
actual operations, perhaps over a long period of time. 

One of the functions of an O.R.S. is clearly to write 
periodical reports on various aspects of operations. 
Except when secrecy questions prevent, these should 
be given a wide circulation, e.g., in the Air Force to 
Squadrons to be read by the aircrews. In this way, 
the tactical education of the men on the job can be 
raised. 

One of the most important duties of a Command is 
to state its requirements for new devices and weapons. 


84 


NDRC BACKGROUND 


Such requirements are pressed, in general, through a 
department of Ministry (which acts partly as a filter 
room, partly as a specialized technical department and 
partly as a post office) to a service technical establish- 
ment. 

The only places in this chain where the real opera- 
tional facts are known is at the Command Groups and 
Stations. Unless the operational requirement is con- 
sidered scientifically at the Command jointly by the 
operational staffs and scientists, it is very possible 
that the operational requirement decided on will not 
correspond (a) to the real need, (b) to the technical 
possibilities. 

In other words, an O.R.S. can act usefully by inter- 
preting 

(a) the practical facts of life to the technical estab- 
lishments, and 

(b) the technical possibilities to the operational staff. 

A considerable wasted war effort has occurred 

through lack of this joint discussion. 

Nothing in this section or in section (b) should be 
taken as implying that an O.R.S. should be the only 
channel by which a Technical Establishment obtains 
operational experience — on the contrary the direct con- 
tact between a Technical Establishment and operational 
units is generally essential. 

An O.R.S. should be an integral part of a Command 
and should work in the closest collaboration with the 
various departments at the Command. 

The head of the O.R.S. should be directly responsible 
to the C. in C. and may with advantage, be appointed 
as his scientific advisor. 

A considerable fraction of the Staff of an O.R.S. 
should be of the very highest standing in science, and 
many of them should be drawn from those who have had 
experience at the Service Technical Establishments. 


Others should be chosen for analytic ability, e.g., gifted 
mathematicians, geneticists, chess players. 

An O.R.S. which contents itself with the routine 
production of statistical reports and narratives will be 
of very limited value. The atmosphere required is that 
of a first class pure scientific research institution, and 
the calibre of the personnel should match this. All mem- 
bers of an O.R.S. should spend part of their time at 
operational stations in close touch with the flying per- 
sonnel, and where possible should occasionally go on 
operational or training flights. 

“New weapons for old” is apt to become a very 
popular cry. The success of some new devices has led 
to a new form of escapism which runs somewhat thus — 
“Our present equipment doesn’t work very well; train- 
ing is bad, supply is poor, spare parts non-existent. Let’s 
have an entirely new gadget!” Then comes the vision 
of the new gadget, springing like Aphrodite from the 
bureaus, in full production, complete with spares, and 
attended by a chorus of trained crews. 

One of the tasks of an O.R.S. is to make possible at 
least an approach to a numerical estimate of the merits 
of a change over from one device to another, by con- 
tinual investigation of the actual performance of exist- 
ing weapons, and by objective analysis of the likely 
performance of new ones. 

In general, one might conclude that relatively too 
much scientific effort has been expended hitherto in the 
production of new devices and too little in the proper 
use of what we have got. Thus, there is a strong 
general case for moving many of the best scientists 
from the technical establishments to the operational 
Commands, at any rate for a time. If, and when, they 
return to technical work, they will be often much more 
useful by reason of their new knowledge of real opera- 
tional needs. 


Chapter 6 

DEVELOPMENT OF U. S. OPERATIONS RESEARCH 

By Philip M. Morse 


T he Navy and NDRC looked upon the estab- 
lishment of an operational research group 
from somewhat different points of view and 
with different expectations. The Navy’s interest 
was at first primarily in the statistical analysis 
of past operations and in assistance in the 
theoretical details of tactical doctrine ; and only 
secondarily in helping to work out military re- 
quirements for gear. The NDRC, on the other 
hand, was interested more in learning about 
the operational behavior of various equipment 
to provide help in the design of new gear. 

From a more general point of view, however, 
the needs were complementary. The NDRC in 
this case was one of the ultimate producers of 
antisubmarine equipment, and the operating 
forces were the ultimate consumers. Between 
these two was a long chain of intermediate 
organizations: the Office of Scientific Research 
and Development, the Navy Coordinator of Re- 
search, the various interested Bureaus of the 
Navy, the Office of the Chief of Naval Opera- 
tions, and finally the Fleets. All this long chain 
of organization was necessary to carry on the 
usual business of development, procurement, 
and supply; the usual flow of requests, orders, 
plans, etc., had naturally to flow along its 
length. But, the chain was too long for tech- 
nical intelligence to flow quickly along it. It 
came to be realized that if some new organiza- 
tion could be devised which could shorten the 
channel of communication with respect to tech- 
nical intelligence, but which would not short- 
circuit the flow of authority in the performance 
of normal duties, this intelligence unit could 
speed up the process of getting new equipment 
into operation and at the same time speed up 
the development of new equipment in the lab- 
oratories. 

From still another point of view, the intro- 
duction of a group of scientists at the opera- 
tional level was an attempt to apply the stim- 
ulus of fresh minds at a new place in the 
organization. Just as it was found useful to 
send officers with operational experience into 
the development laboratories to give the tech- 


nicians an understanding of practical needs, so 
also it was deemed to be useful to try applying 
scientific techniques to tactical planning. 

The introduction of a technical intelligence 
link between the ultimate producer and the 
ultimate consumer was a somewhat delicate 
operation in itself. It was agreed by both sides 
that members of the group should be left in 
civilian status in order to free them from the 
time-consuming duties of the officer. If the 
officer could be likened to the executive of an 
industrial concern, the operational researcher 
was the laboratory worker, not concerned with 
ultimate decisions but with pondering and com- 
paring. Beyond this it was felt that the rules 
of organization of the group would have to be 
worked out as it developed. 


61 ORGANIZATIONAL BEGINNINGS 

As one of the first steps in carrying out the 
commitment made to Captain Baker, Dr. Tate 
on March 20, 1942, asked Dr. Philip M. Morse, 
professor of physics at Massachusetts Institute 
of Technology, to head the new group. The 
possible contributions which the group might 
make to a more effective antisubmarine effort 
promised to be so important that Doctors Tate 
and Morse determined to get the best available 
men for the initial nucleus. Accordingly, not 
only were NDRC laboratories approached for 
personnel contributions, but also laboratories 
and institutions not yet engaged in war work. 
The Bell Telephone Laboratories loaned the 
services of Dr. William Shockley, who became 
the group’s director of research and assistant 
supervisor. Dr. Shockley had just finished work- 
ing on the design of the prototype of the SJ 
submarine radar. The Harvard Underwater 
Sound Laboratory, working under Section C-4, 
contributed two of its staff members, Dr. M. E. 
Bell and Mr. J. R. Pellam. 

Professor S. S. Wilks, who had carried out the 
first statistical studies of depth-charge attacks 
for Section C-4, contributed part of his time 


85 


86 


DEVELOPMENT OF U. S. OPERATIONS RESEARCH 


in getting the group started. He also recruited 
a number of very useful group members from 
among his students and acquaintances in the 
field of mathematical statistics. 


611 Columbia Contract 

Section C-4, NDRC, requested Columbia Uni- 
versity to take on this operational research as 
part of the work under an existing contract, 
OEMsr-20. With Dr. Morse as director of the 
project, and Dr. Shockley as director of re- 
search, the organization was set up as “Group 
M,” one of the five separate activities under 
this contract, coequal with the operations at 
the New London Underwater Sound Laboratory, 
the operations that became known as the Air- 
borne Instruments Laboratory, the work of the 
Special Studies Group, and the operation of 
the Underwater Sound Reference Laboratories. 
It was felt that Group M was a logical addition 
under this contract, for it was believed that 
the studies of Group M would enable New Lon- 
don, and other Section C-4 laboratories to do 
a better job of developing A/S gear. As will be 
seen later, this hope was realized in a number 
of important items. 

During the initial period, the Service liaison 
officer for the group was Captain Baker. 

The group grew slowly but steadily. By May 
1, 1942, there were 7 scientists. By July 1 there 
were 12; by September 1 there were 19 in the 
group and by January 1, 1943, there were 30. At 
the ending of Contract OEMsr-20 on August 31, 
1943, there were 44 members in the group, of 
whom 24 were Ph.D.’s or were full Fellows of 
the Actuarial Societies (equivalent to Ph.D. in 
training). Of these 44, 6 were mathematicians, 
14 actuaries, 18 physicists, 3 chemists, 2 biol- 
ogists, and 1 an architect. The group was re- 
markably cohesive. By the end of August 1943, 
after 17 months of operation, only 2 members 
had left the group. One left to take a commis- 
sion in the Navy, and the other left to return to 
his previous position in another war research 
project. 

At the end of August 1944 there were 50 
members in the group, of whom 28 were Ph.D.’s 
or were full Fellows of the Actuarial Societies. 


This 50 consisted of 7 mathematicians, 16 actu- 
aries, 18 physicists, 5 chemists, 3 biologists, 
and 1 architect. It was decided to give the group 
two names: one, the Anti-Submarine Opera- 
tions Research Group (ASWORG) for use with 
the Navy and for classified reports; the other, 
Research Group M for administrative and 
financial contacts, which were not classified. 


Outline of Organization 

By April 1, 1942, a number of persons had 
agreed to join and the group was given office 
space in the quarters of the ASW Unit, Atlantic 
Fleet, at the headquarters of the First Naval 
District, 150 Causeway Street, Boston, Massa- 
chusetts. The date of April 1 can therefore be 
considered the official birth date of Group M. 
Within a week the first members of the group 
were busy learning their jobs. Records of con- 
voy escort actions were made available, and all 
the officers of the ASW Unit freely contributed 
of their time. 

As the group grew, its members were as- 
signed to various parts of the antisubmarine 
forces. Members were assigned to eastern sea 
frontier, Gulf sea frontier, and Caribbean sea 
frontier headquarters to work with the A/S 
operations officers. A number of members were 
sent to the headquarters of the First Bomber 
Command, AAF and to the Army’s A/S tactical 
development group at Langley Field. Members 
were assigned to London to provide liaison 
with the operational research carried on by 
British forces; and, later, assignments were 
made to Argentia, Newfoundland, to the 
Fourth Fleet in Brazil, and to the Moroccan sea 
frontier in Africa. Others became attached to 
the Navy A/S tactical development unit at 
Quonset, to Seventh Fleet in Australia, and to 
Fleet Air Wing 2, in Hawaii. 

In 1943 it began to be apparent that the pi- 
oneer work of Division 6, in aiding the forces 
in the field, could profitably be applied in other 
fields of activity. Operations Research, Field 
Engineering, etc., were not originally envi- 
sioned in the setup of NDRC. There was some 
fear that such activities were not a legitimate 
part of the work of a division, though eventu- 


MOVE TO COMINCH 


87 


ally every active division found itself engaged 
in them. 

OSRD set up a new office, the Office of Field 
Service [OFS] under Dr. K. T. Compton, to 
handle such activities. The personnel in the 
groups set up by this office were contract em- 
ployees of OSRD, and were loaned directly to 
the Services, under arrangements approved by 
Congress. ASWORG was the first group to 
come under OFS, most of the members being 
transferred from Columbia to OSRD contract 
in January 1944. From this time on, the history 
of Group M or ASWORG is not strictly part 
of the history of Division 6; but the relation- 
ship continued to be very close for some time. 

This, however, is getting ahead of the chron- 
ological story of the Operational Research 
Group. 

FIRST RESEARCH 

Lt. Commander (now Captain) A. B. Vos- 
seller, who represented Naval Air on the ASW 
Unit and who had been particularly active in 
urging the formation of the group, suggested 
that some of its members should visit Norfolk, 
Virginia, to see some of the air antisubmarine 
equipment and planes. Morse, Shockley, and 
Wilks spent an instructive three days at Nor- 
folk, conferring with a number of the pilots at 
the Naval Air Base, looking at equipment and 
being flown in operational aircraft. It was soon 
realized that the work of the group would be 
considerably more useful and practical if the 
members could be kept as closely as possible in 
touch with actual operations, either by frequent 
visits of a similar nature, or perhaps by sta- 
tioning some of the members at outlying bases. 
Operational research could possibly best be 
done nearest to the operations. 

During the first few months at Boston a 
number of studies were commenced, some of 
which were later to occupy the group’s atten- 
tion a great deal. The whole complex of prob- 
lems which might be considered together under 
the single word “Search” soon became impor- 
tant. General search principles were laid down 
which have been subsequently changed only in 
detail. From these principles aerial escort of 


convoy plans were laid out, as well as search 
plans for surface escort. A more complete dis- 
cussion of this problem will be given later in 
this review. 

Detailed statistical analysis of operations 
was not commenced at first, partly because the 
Navy facilities for the collection of operational 
reports were not complete as yet. But some 
initial analysis of surface vessel attacks was 
made ; and various members of the group were 
asked to contribute suggestions as to the mate- 
rial and form of the action reports, which were 
supposed to be filled out in case of an attack 
or sighting. 

63 MOVE TO COMINCH 

In the meantime, Captain Baker, head of the 
Atlantic Fleet ASW Unit, had been called to 
Washington for a series of conferences. It was 
to be expected that the headquarters of the 
Commander-in-Chief, U. S. Fleet, would be the 
proper place for central tactical planning for 
antisubmarine warfare, since only from there 
could doctrine be sent out which would be used 
by sea frontiers as well as by the Fleets. About 
the end of May 1942, therefore, Captain Baker 
was transferred to the Readiness Division of 
the COMINCH staff, where he was directed to 
set up an antisubmarine unit. He did this by 
bringing down some of the members of the 
Atlantic Fleet ASW Unit, by taking over the 
officer who had previously held the COMINCH 
ASW desk, Commander C. R. Todd, and by 
bringing in a few new officers. 

At the same time Captain Baker was instru- 
mental in setting up an antisubmarine unit in 
the eastern sea frontier headquarters, in New 
York City. Commander (later Captain) Hun- 
gerford was brought in to head this unit and 
the Army Air Officer, Lt. Col. Cecil Reynolds, 
who had previously been with the Boston unit, 
was brought to New York to provide liaison 
with the First Bomber Command AAF. Com- 
mander (now Captain) T. L. Lewis was left in 
charge of the Atlantic Fleet unit in Boston, 
and a few additional officers were brought in 
to complete his complement. Plans at one time 
were made for the setting up of a similar unit 


88 


DEVELOPMENT OF U. S. OPERATIONS RESEARCH 


at Gulf sea frontier in Miami; this, however, 
did not eventuate. 

Plans also were made for the expansion of 
the activities of Group M in order to keep pace 
with this naval expansion. In June 1942, offices 
were obtained for the group in Temporary 
Building 2, opposite the Navy Department, in 
Washington. The main headquarters of the 
group was gradually transferred from Boston 
to Washington, leaving only four members 
with the Atlantic Fleet unit. After a few 
months, offices for the group were found in the 
Navy Department on Constitution Avenue. 
After one or two moves the group found its 
permanent location in the series of rooms 4303 
to 4313, in the main Navy Building, which it 
has occupied ever since. 

On the first of July members of the group 
were installed at eastern sea frontier, report- 
ing to the ASW unit there. Here, closer rela- 
tionship was established with the Army Air 
Forces First Bomber Command, which pro- 
vided many of the long-range bombers used in 
antisubmarine patrols along the eastern coast. 
A number of the Army air fields were visited, 
in particular Langley Field, where a certain 
amount of tactical and equipmental experimen- 
tation was being carried out under Colonel 
W. C. Dolan. 


64 ASSIGNMENT TO BASES 

Also in June 1942, Dr. Shockley, together 
with Dr. A. F. Kip, visited the headquarters of 
Gulf sea frontier in Miami. As a result of that 
visit and the previous negotiations of Captain 
Baker, Dr. Kip was left on assignment with the 
Operations Officer of Gulf sea frontier. In July, 
Dr. Shockley made a similar trip to Caribbean 
sea frontier with Dr. R. F. Rinehart, who was 
then assigned to the Operations Officer at the 
headquarters in San Juan, Puerto Rico. Later 
he was transferred to the headquarters of the 
Trinidad sector of this frontier. 

In November, Dr. Bell and Mr. Pellam went 
to the base at Argentia, Newfoundland, the 
headquarters of Commander Task Force 24, 
who had command of the American escort ves- 
sels escorting the transatlantic convoys over 


the American half of the trip. After this visit 
a request came to Washington for a man 
from the group to be assigned to the Task 
Force. In the middle of December, Dr. F. L. 
Brooks was sent to Argentia, where he stayed 
until a realignment was made in convoy 
escort responsibilities. As a result of a joint 
USN-Admiralty agreement to transfer North 
Atlantic convoy control to the British after 
April 1943, Dr. Brooks’ services were no longer 
necessary at Task Force 24, and he returned to 
Washington at that time. 

In January 1943 a request for a Group M 
member came from Commander, Fourth Fleet, 
Vice Admiral J. H. Ingram, whose headquar- 
ters were at Recife, Brazil, and who had the 
responsibility for antisubmarine warfare on 
the American side of the South Atlantic. Dr. 
J. J. Steinhardt was sent first to Trinidad with 
Dr. Rinehart for some base experience, eventu- 
ally arriving at Recife to report to Admiral 
Ingram on the first of March 1943. 

Other bases were also set up. The numerous 
letters of commendation received from the cog- 
nizant officers concerning the work of mem- 
bers of the group indicate that an important 
part of Group M’s work was done at these out- 
lying bases. This is not surprising for, although 
the general principles of tactics and military 
requirements for equipment can perhaps best 
be worked out at a central headquarters such 
as Washington, the detailed application of the 
general principles must usually be worked out 
at an operational base. This detailed local help 
was useful in teaching the application of the 
general principles to the local forces and was 
also immensely valuable in teaching ASWORG 
men the practical aspects of the problem. Also, 
Group M base men proved to be of use in col- 
lecting operational data of a detailed nature, 
and in transmitting these to Washington for 
analysis. 

By the end of the first year of operation, a 
number of general conclusions as to organiza- 
tion were apparent. In the first place, in order 
that the group remain mentally healthy and 
scientifically aggressive, it was necessary that 
a fair percentage of its members be assigned 
to outlying bases where actual operations were 
going on. It was important that these men be 


RELATIONS WITH THE ARMY AIR FORCES 


89 


attached to the higher echelons of the various 
outlying task forces, so that the problems aris- 
ing could be assigned to them quickly and their 
solutions could be returned quickly for possible 
action. 

The operational forces controlled from these 
outlying bases were the ultimate users of the 
antisubmarine equipment, so that the useful- 
ness or the difficulties involved in a new piece 
of apparatus could be best determined by one 
of the base men. New needs, either for tactics 
or for equipment, were often discovered first at 
these bases. Changes in enemy tactics which 
were discovered by the group were usually dis- 
covered by one or another of the base men. 


65 WASHINGTON OFFICE 

The central headquarters in Washington had 
individual importance. At the Navy Depart- 
ment, the official orders were issued and the 
general doctrine was written. Here, the experi- 
ence of the various base members could be 
crystallized into suggested doctrine or orders 
for equipment or development work. Here, the 
reports of all the base men and the action re- 
ports from all of the antisubmarine forces 
could be collected and studied statistically. 
Here, contact could be maintained with the 
naval and NDRC laboratories. General theo- 
retical analyses could be worked up in Wash- 
ington, and the results sent out to the base men, 
who were usually too busy to work out long 
and detailed calculations. Correlated results 
from all the bases could be sent back out to the 
bases so that each could see how the others 
were doing. All the work could be supervised 
by the proper naval authorities, clearances 
could be given, permission for publication and 
distribution could be obtained, and the general 
terms of reference of the group with the related 
services could be maintained. 

It also became clear that there should be a 
certain amount of rotation between base men 
and central office men. Each man at each base 
should return to Washington at least every six 
months, so that he might catch up on new de- 
velopments at home, and might give the home- 
office men the benefit of his experience. While 


he was absent from his post, his place would 
be taken by a home-office man who needed such 
field experience. 

In view of this interrelation between base 
and central office in Washington, it is not sur- 
prising that the make-up of the central office 
was at first preponderantly statistical. As the 
base men began to return from their first tours 
of duty, a greater percentage of men trained 
in the physical sciences could be maintained in 
Washington. By then the group had matured. 


6 6 RELATIONS WITH THE ARMY 
AIR FORCES 

At about the time that the eastern sea fron- 
tier unit was organized and several Group M 
members were assigned to New York, the group 
began to be acquainted with the activities of the 
staff of Brigadier General Westside T. Larson, 
commander of the First Bomber Command, 
Army Air Forces. This Command, among other 
duties, supplied long-range bombers for anti- 
submarine patrol, under the operational control 
of the Eastern Sea Frontier. Its offices were at 
90 Church Street, the same building which 
housed the Eastern Sea Frontier headquarters. 
Dr. Shockley and a number of other group 
members visited several of the First Bomber 
Command airfields to learn firsthand the Army 
problems in antisubmarine warfare. 

Shortly thereafter the group was brought 
into contact with Dr. E. L. Bowles, scientific 
consultant to the Secretary of War, who at this 
time was much interested in the use of radar 
in antisubmarine operations. Search radar in- 
stalled on aircraft was promising to be of con- 
siderable use in finding surfaced submarines, 
by day as well as by night. The first studies made 
by Group M on the operational flying of First 
Bomber Command radar planes indicated that 
average radar ranges of first sightings of sub- 
marines were definitely larger than average 
visual ranges of first sightings. 

Dr. Bowles put the group in contact with 
Brigadier General H. M. McClelland, at that 
time Director of Technical Services of the 
Army Air Forces, who had cognizance of radar 
problems for the Air Forces. The experience 


90 


DEVELOPMENT OF U. S. OPERATIONS RESEARCH 


of his staff, in particular of Dr. Dale Corson, 
was of considerable benefit to Group M in com- 
mencing the study of the operational use of 
radar. Dr. Corson had worked at Radiation 
Laboratory, then had become one of Dr. Bowles’ 
assistants, and had been assigned to General 
McClelland. In December 1942, General Mc- 
Clelland was named a liaison officer for Group 
M, and in May 1943, General Larson was also 
made liaison officer. 


6 7 SEA SEARCH UNIT 

In the summer of 1942 it was decided by the 
Army that it would be useful to set up a sea 
search attack and development unit to study 
the tactical and equipmental problems of anti- 
submarine operations by aircraft. This unit 
was organized under Colonel Dolan and in- 
stalled at Langley Field, Virginia. During its 
period of operations, it worked on and was 
instrumental in getting into service the SCR 
517 and 717 search radar, the magnetic air- 
borne detector equipment [MAD], searchlights, 
and bombsights for antisubmarine aircraft op- 
eration. 

For various reasons, the Sea Search Attack 
and Development Unit [SADU] was not placed 
under the control of the First Bomber Com- 
mand but was under the control of General Mc- 
Clelland’s office, the Directorate of Technical 
Services, Army Air Forces. Colonel E. E. 
Aldrin of General McClelland’s office was the 
supervisory officer in Washington and was 
made liaison officer for the group in April 1943. 

The first week in September 1942, H. H. Hen- 
nington, a Group M member, was sent to Lang- 
ley to work under Colonel Dolan for SADU. 
By winter it was apparent that more men would 
be needed to work on the problems which 
Colonel Dolan was assigning the group, so Dr. 
Bell was transferred from the Boston office of 
the ASW Unit Atlantic Fleet to head the Lang- 
ley group. D. D. Cody was also assigned there 
in February 1943. 

This group of ASWORG members worked on a 
variety of problems during their stay at Langley. 
It helped to some extent in arranging contacts 
between NDRC laboratories and the Develop- 


ment Unit. It helped to prepare programs for 
tactical tests and then to write up the reports 
of the tests. A series of exercises was devised 
to check the proficiency of crew and gear in 
low-level bombing, such as is used in A/S at- 
tacks. Programs and reports were written on 
tests of sono buoys, searchlights, forward-fir- 
ing rocket-flares, bombsights, odographs, and 
other equipment which might be of use in A/S 
operations. A full-dress tactical test of MAD 
tactics at Key West was supervised by Cody. 
Before SADU was closed, Group M members 
had been instrumental in the publishing of an 
Army manual, “Operational Use of Radar in 
Sea Search.” 


6 8 ANTISUBMARINE COMMAND 

In the fall of 1942 also came a request from 
General Larson to assign one or more men to 
the headquarters of the First Bomber Com- 
mand, which about that time became the Anti- 
Submarine Command, AAFAC. In October, Dr. 
A. A. Brown and M. E. Ennis, Group M mem- 
bers, were assigned to AAFAC headquarters, 
with Dr. Brown as head of the unit. In Decem- 
ber, A. W. Brown also was assigned to this 
unit. This group worked on problems of train- 
ing and material for the AAFAC staff. A com- 
plete study and report was made of all types of 
bombsights, resulting in a subsequent series of 
development projects at Wright Field and else- 
where to perfect a suitable antisubmarine sight. 
Coordinate grids were developed to measure 
photographs of A/S attacks, and a procedure 
was evolved to obtain adequate photographic 
coverage of all attacks. Group members accom- 
panied various officers of the AAFAC staff on 
their inspection trips, in order to provide spe- 
cialized advice on the spot. 

In the meantime Brown was assisting in the 
writing and editing of the AAFAC Monthly 
Intelligence Report. He worked up the A/S 
operational statistics for the monthly report 
and wrote many of the articles on equipment 
and tactics. 

During the winter of 1942-43 the Anti-Sub- 
marine Command established a special antisub- 
marine operational training unit, the 18th 


RELATIONS WITH THE BRITISH 


91 


Squadron, based at Langley Field. Lt. Colonel 
R. W. Finn, the squadron commander, re- 
quested the aid of ASWORG in setting up a 
program of tactical training. Dr. G. R. Pomerat 
was assigned there in May 1943 and stayed 
through the summer. He helped in establishing 
lecture schedules, training flight schedules, and 
standards for bombing exercises. He had begun 
work on the scenario for an antisubmarine 
training film when the training unit was dis- 
continued in the fall. 


69 RELATIONS WITH THE BRITISH 

By the fall of 1942, the group’s directors, 
Doctors Morse and Shockley, felt themselves 
to be well enough acquainted with the Amer- 
ican antisubmarine problems so that a visit to 
England would be profitable. It was thought 
likely that one or more of the group members 
should stay in England continuously to form 
liaison with the British antisubmarine forces, 
and in particular with the Coastal Command 
and Admiralty Operations Research Groups. 
Captain Baker’s permission for Dr. Shockley 
and Dr. Morse to go to England was granted 
in November. 

After the plans for the trip had been made, 
another development occurred which made the 
trip particularly timely. 

In order to assist the British Coastal Com- 
mand in the antisubmarine air patrol of the 
Bay of Biscay, it was decided in the fall of 1942 
that the United States Army Air Forces should 
contribute a squadron or two of antisubmarine 
planes. It was contemplated that these planes 
should participate in the particularly heavy air 
patrol of the Bay planned for the time of the 
landing in North Africa. The planes were to be 
sent first to England to help in the Bay patrol 
and then later to Africa to operate against sub- 
marines in African coastal waters. 

The first squadron was hastily assembled and 
was sent off to England November 1, 1942, 
under the command of Lt. Colonel Jack Rob- 
erts. It was based in England at St. Eval, Corn- 
wall, and was operationally controlled by the 
British. Since this squadron had been supplied 
by the Anti-Submarine Command, General Lar- 


son asked Morse and Shockley to look it up 
when they got to England, and to give the 
squadron what technical help they could. 

6-91 Liaison with British Operations 
Research 

Doctors Morse and Shockley arrived in Eng- 
land about the middle of November 1942. Cap- 
tain Baker had arranged for them to report to 
the Naval Attache’s office in London. They were 
assigned to Captain T. A. Solberg, head of the 
Technical Section of the Attache’s office. In this 
office also were other civilian scientific experts, 
representatives of the Bureau of Ships, Naval 
Ordnance Laboratory, etc., maintaining scien- 
tific liaison with the corresponding British Bu- 
reaus and laboratories. Captain Solberg was in- 
strumental in arranging a number of valuable 
contacts for Morse and Shockley. 

Since, to facilitate travel authorizations, the 
men went over as special OSRD representa- 
tives, they also reported to Bennett Archam- 
bault, head of the OSRD London office, who also 
arranged for liaison with British war research 
laboratories, for office space, and for transpor- 
tation facilities. Archambault gave very valu- 
able aid in arranging contacts for the two mem- 
bers. 

A great number of such contacts had to be 
made. In the first place there was Admiralty, 
which had operational responsibility for anti- 
submarine warfare, routed the convoys, con- 
trolled the destroyer escorts on their side of 
the Atlantic, and which also had operational 
control over the Coastal Command’s antisub- 
marine planes. Meetings were arranged with 
Captain Philip Clark, Director of Anti-Sub- 
marine Warfare [DASW], with Professor 
Blackett [CAOR], and with other operational 
research people working in antisubmarine war- 
fare, among them being Dr. J. H. C. Whitehead 
and Dr. E. C. Bullard. The work of these peo- 
ple was discussed with them, and arrange- 
ments were made for the future interchange of 
ideas and reports. 

The next contacts were with Coastal Com- 
mand. Arrangements were made to go to 
their headquarters to meet the head of Op- 


92 


DEVELOPMENT OF U. S. OPERATIONS RESEARCH 


erations Research Section, Coastal Command 
[ORS/CC], at that time Professor Williams. 
A meeting was held with the head of Coastal 
Command, Air Chief Marshal Philip Joubert. 
The particular problems of the AAFAC squad- 
ron at St. Eval were discussed at this meeting, 
and it was agreed that Dr. Shockley was to 
spend the majority of his time with Colonel 
Roberts’ squadron until it got under way. 

Soon afterward Dr. Shockley went to St. 
Eval and established contact with Lt. Colonel 
Roberts and the Squadron of B-24’s which was 
there. It turned out that this squadron was 
the first operational squadron of antisubmarine 
planes in England to have S-band radar sets. 
This produced many complications since all the 
British plans, arrangements for blind landings, 
etc., were built around the longer wave ASV 
Mark II sets. This, combined with the fact that 
the American squadron had been assembled in 
a hurry and had not had a thorough radar 
training, meant that the inherent advantages of 
the S-band gear were not immediately realized. 
After numerous discussions, the squadron was 
allowed extra time to spend in further train- 
ing, and it was just about in shape when it was 
transferred to a base in Casablanca, North 
Africa. It subsequently proved most useful 
there; and mention will be made of its opera- 
tions in the sections dealing with the work of 
ASWORG men assigned to Moroccan sea fron- 
tier. 

At the meeting with Air Chief Marshal Jou- 
bert and at other subsequent ones, arrange- 
ments for liaison with ORS/CC were worked 
out. These arrangements were materially aided 
by the presence of J. P. T. Pearman, a pioneer 
member of ORS/CC, who was familiar also with 
our research program. Earlier in 1942, Pear- 
man had visited America at the time a Coastal 
Command squadron was sent here to help out in 
antisubmarine work in the Caribbean. Pearman 
had made contact with ASWORG and had spent 
considerable time in bringing the group up to 
date on the work of ORS/CC. He had returned 
to England early in the fall and was on hand 
at Coastal Command to welcome the visiting 
ASWORG members and to introduce them to 
people at the headquarters. 

Professor Blackett arranged for Dr. Morse 


to meet Colonel (now Brigadier General) 
Schonland, head of the Army Operations Re- 
search Group. A visit was made also to the 
Eighth Bomber Command, U. S. Army Air 
Forces, and to the Army Operations Research 
Group assigned to that Command. This group, 
under J. M. Harlan, had just recently arrived 
and was busy exploring the problems with 
which it would be called upon to deal. 


6 9 2 London Office 

As one of the results of their visit to Eng- 
land, Doctors Morse and Shockley became con- 
vinced that at least two ASWORG men should 
be kept in England to provide liaison with the 
British antisubmarine operations research 
work. These members could be assigned to Com- 
mander Naval Forces in Europe [ComNavEu] 
and would work under the direction of Captain 
Solberg. One of these two men could spend most 
of his time in liaison with ORS/CC, and the 
other could spend most of his time at Admiralty 
with the operations research workers there. 
This idea was welcomed by the British workers 
and was also satisfactory to Captain Solberg. 
Upon the return of Dr. Morse to this country 
the plan was formalized with Navy approval. 


6 10 INCORPORATION INTO THE 
TENTH FLEET 

By the end of 1942 it had become clear that 
improvement in the quantity and quality of 
antisubmarine equipment and personnel could 
not by itself win the battle of the Atlantic. A 
centralized planning and operational authority 
was needed. 

There were numerous examples of divided 
authority, resulting inevitably in reduced ef- 
fectiveness. The squadrons of the First Bomber 
Command (later the Anti-Submarine Com- 
mand), AAF were controlled operationally by 
the eastern sea frontier. Later, a few of the 
squadrons were assigned to England, where 
they were controlled by the Coastal Command, 
RAF. Several squadrons were subsequently 
sent to Africa where they were under still an- 


INCORPORATION INTO THE TENTH FLEET 


93 


other operational command. Army squadrons 
were supplied to the Caribbean sea frontier by 
the First Antilles Air Task Force (later the 
Antilles Air Command) of the Army Air 
Forces. 

It was suggested by some in the AAF that 
all of the Army air antisubmarine effort be 
unified under the Anti-Submarine Command, 
which would have its squadrons eventually all 
around the North Atlantic. This would have 
provided a certain unity as far as training 
and equipment went, but the operational con- 
trol of these Army planes would still have been 
divided. In addition there was the situation of 
the more or less autonomous sea frontiers, each 
with its own tactical doctrine, planning staff 
and intelligence organization. 

During the spring of 1943, the Commander- 
in-Chief’s staff was engaged in a detailed study 
as to the best organizational means of improv- 
ing this complex command relationship. The 
time was opportune for some central authority 
to be placed over all of these activities to deter- 
mine unified doctrine, to arrange for unified 
distribution of intelligence, and to unify oper- 
ational planning. Resulting from these studies, 
the Tenth Fleet was established in May 1943 
under the direct command of Admiral (later 
Fleet Admiral) E. J. King, Commander-in- 
Chief, U. S. Fleet, with Rear Admiral F. S. Low 
as Chief of Staff. 


Improvement of ASWORG 
Effectiveness 

The complications due to the divided com- 
mand naturally had affected the work of Group 
M. Those assigned to the Anti-Submarine Com- 
mand of the Army found themselves working 
with plans for training and materiel which 
were often at variance with the Navy plans 
for naval aircraft. Tactical doctrine differed 
and there was a certain amount of rivalry in 
pushing new equipment developments, which 
made for duplication of technical effort. The in- 
terpretation and use of operational doctrine 
and intelligence differed from frontier to fron- 
tier. Group M members assigned to outlying 
bases often had found themselves to be the sole 


messengers of unified doctrinal planning, which 
sometimes led to embarrassments in Command 
relations. 

This lack of unified authority had particu- 
larly hampered the work of the Washington 
office of Group M. Many of the statistical and 
analytical studies of the group directly sug- 
gested new operational procedures. There had 
been no central authority to whom to report 
these suggestions nor one who could take action 
on them if action was deemed advisable. Lack 
of central operational authority meant that 
the Washington office could not carry on oper- 
ational research in the strict sense of the word. 

As the direct result of the establishment of 
the Tenth Fleet, Group M was enabled to work 
more effectively. Under the careful and under- 
standing guidance of Admiral Low and his 
staff, its research improved greatly. 

One of the first tasks of the Tenth Fleet was 
to settle the question of the Army’s part in the 
antisubmarine effort, and, in particular, to 
study the recommendation that all Army A/S 
flying be unified under the Anti-Submarine 
Command. This unification appeared desirable, 
but from a more general point of view it would 
have introduced an inevitable duality between 
the Army and the Navy antisubmarine flying. 
The Army had originally been asked to con- 
tribute to antisubmarine flying because at the 
beginning of World War II the Navy planes 
were needed elsewhere and the Army had 
planes available along the east coast. By the 
first of 1943 this situation had changed to some 
extent. Although Navy planes were not easily 
obtainable, there were enough to spare from 
Pacific operations to make it possible for the 
Navy to begin taking care of all antisubmarine 
flying in the Atlantic. This, of course, would 
result in a much greater unity in the effort and 
if a decision to relieve the AAF of A/S duties 
were to be made eventually, it could best be 
made at the time of formation of the Tenth 
Fleet. 

Consequently, it was decided by high au- 
thority that the Navy would gradually take 
over all the antisubmarine effort in the At- 
lantic, that the squadrons of the Army Air 
Forces Anti-Submarine Command in England 
and in Africa would eventually be replaced by 


94 


DEVELOPMENT OF U. S. OPERATIONS RESEARCH 


naval squadrons, and that the Anti-Submarine 
Command would be returned to its original po- 
sition of First Bomber Command. This was 
gradually accomplished during the first half of 
1943; the squadrons under Lt. Col. Roberts, 
which had first been sent to England and then 
to Africa, being among the last ones to be re- 
placed. 

During this same time, the activities of 
Group M that had been connected with the 
Army’s antisubmarine effort were correspond- 
ingly curtailed, and its activities at the various 
naval bases were being increased. The 
ASWORG unit at Langley Field was closed in 
August, and the men assigned to AAFAC head- 
quarters in New York were returned and given 
other assignments. Mr. Pellam, who had been 
sent over to England to work with Lt. Col. Rob- 
erts’ squadrons and who had accompanied the 
squadrons to North Africa, transferred his 
allegiance to the naval authorities at Moroccan 
sea frontier. The change was authorized by the 
Tenth Fleet, as were the other changes. 


Relations with Tenth Fleet 

In the meantime, Group M was made an offi- 
cial part of the Tenth Fleet. After discussions 
between Admiral Low and Dr. Tate, Chief of 
Section C-4 (by then Division 6) NDRC, a di- 
rective was written by Dr. Tate on July 7th and 
endorsed by Admiral E. J. King on July 9th de- 
fining the activities of Group M and its rela- 
tion to the Tenth Fleet. The official name of the 
group was given as the Anti-Submarine War- 
fare Operations Research Group [ASWORG] 
although the title “Group M” was continued 
with the Columbia University administrative 
department in order to maintain security. 

The Tenth Fleet was, in a way, a fifth divi- 
sion of the COMINCH staff, the other four di- 
visions being Plans (FI), Combat Intelligence 
(F2), Operations (F3) and Readiness (F4). 
Admiral Low was appointed Assistant Chief of 
Staff (antisubmarine) of COMINCH, and Chief 
of Staff of Tenth Fleet (FX). The staff of 
Tenth Fleet paralleled in part the standard 
naval staff, having an operations section 
(FX-30) and a readiness section, which in this 


case was called A/S Measures (FX-40). Con- 
voy and Routing, under Rear Admiral M. K. 
Metcalf, was made FX-37. ASWORG was 
placed under A/S Measures, and the head of 
ASWORG, Dr. Morse, became FX-45. 

The original head of the COMINCH Anti- 
Submarine Unit, Captain Baker, had returned 
to sea in November 1942, his replacement being 
Captain J. M. Haines. When the Tenth Fleet 
was formed, Captain Haines became head of 
Measures, FX-40, and ASWORG reported to 
Admiral Low via Captain Haines. In Septem- 
ber 1943, Captain Haines also returned to sea, 
his replacement being Captain H. C. Fitz. 


611 ASDEVLANT 

About the same time that the Tenth Fleet 
was being formed, another need, long felt by 
the Navy Antisubmarine Forces, was satis- 
fied; a need for an organization which would 
carry on tactical experimental work in anti- 
submarine operations and which would also 
provide operational training for antisubma- 
rine air crews. This need had been met for the 
Army by the establishment of SADU and an 
operational training unit [OTU] at Langley 
Field. These units were not under the same 
command, SADU having been under the Direc- 
tor of Technical Services, General McClelland, 
and the OTU under AAFAC. 

In the case of the Navy, the first move in this 
direction was the establishment in February 
1943 of the Aircraft Anti-Submarine Develop- 
ment Detachment, Atlantic Fleet [AirASDev- 
Lant]. This unit was under Commander Air 
Forces, Atlantic Fleet [ComAirLant], and 
combined the activities of the tactical develop- 
ment unit and the specialist training unit. The 
Commanding Officer of the Detachment was 
Captain Vosseller, who had been with the At- 
lantic Fleet A/S Unit in Boston, and who had 
been connected with the early developments of 
ASWORG. The unit was located at Quonset 
Point, R. I. 

Shortly after its formation, AirASDevLant 
requested the assignment of several ASWORG 
members. Doctors C. F. Squire and W. J. Hor- 
vath were sent in May 1943, and Dr. Bell was 


OTHER FIELDS 


95 


sent in July, as soon as he could finish his work 
for SADU, at Langley Field. The ASWORG 
Unit at Quonset worked on a great variety of 
problems for ASDevLant. They helped devise 
tactical and operational tests of new equipment, 
and helped to write manuals and tables to aid 
in the use of some of this equipment. Assistance 
was given in tests of various types of low-alti- 
tude bombsights, calculations were made for 
proper sighting and intervalometer settings 
for glide bombing, operational procedures were 
computed and tested for rockets, and a variety 
of tests were devised and analyzed concerning 
visual and radar sightings. The group mem- 
bers were active in helping to devise methods of 
utilizing sono buoys, a development of the Di- 
vision 6 New London laboratories. Tactics for 
searchlight planes were also a subject for in- 
vestigation. 

In July, the responsibilities of AirASDev- 
Lant were broadened to include tactical experi- 
mental work with surface craft, and the name 
of the unit was changed to Anti-Submarine De- 
velopment Detachment [ASDevLant] . The 
original unit became the Aircraft Division of 
the new detachment and a new, coequal Sur- 
face Division was added. Arrangements were 
made in the activating directive for very close 
coordination between the detachment and 
Tenth Fleet, and Tenth Fleet undertook to pro- 
vide ASDevLant with ASWORG members to 
assist both divisions. 

Dr. R. M. Elliott was assigned to the Surface 
Division and assisted Comdr. H. R. Hummer, 
the head of the Surface Division, in tests of 
various sonic and other detection gear. He 
assisted in the devising and interpreting of 
tests of various countermeasure equipment. 
J. K. Tyson also assisted the Surface Division 
at ASDevLant by analyzing trials of surface 
vessel attack procedure. By the end of 1943 
there were six ASWORG members assigned to 
ASDevLant. 


6 12 OTHER FIELDS 

An extremely important development in anti- 
submarine warfare in 1943 was the appearance 
of the carrier escort group. In order to study 


at first hand the problems peculiar to this op- 
eration, Dr. W. E. Albertson, a group member, 
was sent on an operational trip. On his return, 
work was commenced on CVE (Convoy Escort 
Carrier) tactics which will be discussed later. 

Group M meanwhile had grown to consist of 
approximately 50 members. 

By the fall of 1943 it began to be apparent 
that operational research could be of use to the 
Navy in studying other than antisubmarine 
problems. It came to be understood that, as the 
antisubmarine war receded, the efforts of 
Group M would be gradually transferred to 
other problems. The first development was in 
the direction of aiding our own submarines. 
This came about partly due to the relationship 
with Division 6 NDRC, which was the division 
concerned with Subsurface Warfare, and in- 
terested in the development of equipment for 
our own submarines as well as for antisub- 
marine craft. 

In order to find out the ways in which Divi- 
sion 6 could be of aid to our submarine forces 
in the Pacific, Dr. Tate visited Pearl Harbor 
and discussed the situation with Commander 
Submarines, Pacific Fleet [ComSubPac]. 
Shortly thereafter a request came to the Tenth 
Fleet for the assignment of several ASWORG 
members to Pearl Harbor to assist the Com- 
SubPac staff. In November 1943 Doctors G. E. 
Kimball and R. F. Rinehart were sent to Pearl 
Harbor, Dr. Kimball to return in a month, and 
Dr. Rinehart to stay on at Pearl Harbor. 

Later, four other Group M members were 
sent to work under Dr. Rinehart for ComSub- 
Pac, and an IBM machine setup was installed 
at Pearl Harbor for their use. A great number 
of important and interesting problems were 
solved by this group. A corresponding subma- 
rine group was set up in Washington to work 
on statistical and analytical problems. This 
group, headed by Dr. Charles Kittel, was loaned 
by Tenth Fleet to the head of the submarine 
desk in COMINCH Readiness, first Comdr. 
E. E. Yeomans and later Comdr. C. C. Smith. 
Capt. A. R. McCann, at the submarine desk, 
Naval Operations, Fleet Maintenance (later 
taken over by Capt. F. T. Watkins) was named 
as joint supervisory officer. The two groups at 
Pearl Harbor and at Washington, working on 


96 


DEVELOPMENT OF U. S. OPERATIONS RESEARCH 


problems for our own submarines, were infor- 
mally labeled as SORG to distinguish them 
from the main group, ASWORG. 

In 1944, other opportunities opened for 
Group M members to be assigned in the Pa- 
cific. Vice Admiral T. C. Kincaid, Commander 
Seventh Fleet, in the Southwest Pacific area, 
requested an antisubmarine analyst for his 
staff. Dr. Steinhardt, who had been with 
Fourth Fleet in Brazil, was assigned to this 
position and sent to Brisbane, Australia in 
March 1944. He returned in August and A. M. 
Thorndike was sent out to take his place. In 
June, R. E. Traber was sent to Hawaii to work 
with the Anti-Submarine Training Unit in 
Fleet Air Wing 2 (FairWing 2). After a short 


stay he was replaced, as had been agreed upon 
originally, by Gordon Shellard, who had re- 
turned from Trinidad. 

In October 1944, the whole group was trans- 
ferred back to Readiness Division, COMINCH, 
and was reconstituted as ORG, a part of the 
Research and Development Section, F-45. Dr. 
Morse became director, F-450, of Operations Re- 
search Group. ASWORG became a subgroup 
assigned back to Tenth Fleet, and other sub- 
groups, SORG, AirORG, AAORG, PhibORG, 
were formally organized and assigned to the 
appropriate parts of COMINCH staff, CNO, 
or to Fleet Commands. By this time the group 
had become a recognized part of the naval staff 
organization. 


Chapter 7 

RESEARCH ACTIVITIES 

By Philip M. Morse 


O perational research may be arbitrarily 
divided into three main categories : statis- 
tical, analytical, and materiel. The statistical 
part of the work consists of the collection and 
statistical analysis of operational data, espe- 
cially those from action reports of various op- 
erations. The more detailed the assessments 
of the success of the actions, the more useful 
will be the analysis, for the aim of statistical 
studies in operational research is to determine 
the most effective type of operation and not to 
provide a history of the past. The analytical 
part consists of combining knowledge concern- 
ing past operations with specialized knowledge 
concerning the behavior of equipment, in order 
to work out theoretically the best tactics to use 
in a new situation. The materiel part consists 
of the detailed study of the characteristics of 
new apparatus in order to indicate its most 
effective employment in operations and the de- 
tailed study of the behavior of equipment in 
action in order to recommend modifications in 
design or development of new equipment. In 
practice, no hard and fast line can be drawn be- 
tween these categories, and most problems 
studied by Group M have had their statistical, 
analytical, and materiel aspects. 

71 PUBLICATIONS 

The results of Group M’s studies were pub- 
lished in a variety of forms. Whenever the re- 
sults were generally applicable, and if the 
COMINCH staff deemed them worthy of dis- 
tribution to some part of the operating forces, 
these studies were published as ASWORG 
Memoranda, with a distribution list approved, 
by COMINCH. After the formation of the 
Tenth Fleet, resumes of most of the reports 
of this type were published in the U. S. Fleet 
Anti-Submarine Bulletin, the monthly official 
publication. Results of studies giving basic 
theory or mathematical techniques, which were 
not of general interest to the operating forces 
but which provided a useful basis for further 


operations research, were published as Inter- 
Office Bulletins [IOB]. These publications, 
after receiving Tenth Fleet approval, were sent 
to Group M members at the various operational 
bases, but were not for general distribution to 
Service personnel. Results of research, in re- 
sponse to specific requests or requests having 
limited interest, were usually published (after 
August 1943) as Research Reports [RR]. 
Many of these latter reports were handed only 
to the proper official in Tenth Fleet (via FX- 
40), and had no other distribution at all. These 
were kept on file to be of possible help in future 
work. A few have had somewhat wider, al- 
though still very limited, distribution. 

By August 31, 1943, Research Group M had 
published : 

40 Memoranda 

13 Articles in the U. S. Fleet Anti-Subma- 
rine Bulletin 

12 Inter-Office Bulletins 
1 Research Report 

By August 31, 1944 the list had swelled to: 

45 Memoranda 

52 Articles in the Anti-Submarine Bulle- 
tin 

22 Inter-Office Bulletins 

64 Research Reports 

After the group was reconstituted as ORG 
in the Readiness Division, the report system 
had to be expanded. Four general categories 
were set up. 

1. Memoranda — These consisted of results 
of short studies, usually in response to specific 
requests, and usually were distributed only to 
the officer making the request. Memoranda hav- 
ing no circulation outside the group were called 
“Memoranda for File.” 

2. Studies — These were reports on research 
involving more than one or two man-days of 
work, whose form and content had been ap- 
proved by the responsible subgroup super- 
visor. Studies also had only a limited circula- 
tion outside the group, but they constituted a 
fairly complete record of the work carried on 
by each subgroup. The studies of each sub- 


97 


98 


RESEARCH ACTIVITIES 


group were given distinctive labels: RR’s for 
ASWORG, CC’s for ORG, SS’s for SORG, etc. 

3. When a study received fairly widespread 
approval from the group, and when there were 
requests for fairly widespread distribution to 
the Navy, the study, after editing and approval 
by the proper authorities, was reissued as an 
ORG Report, or Publication. 

4. Portions of studies sometimes appeared 
as ORG contributions in the form of articles 
in some official naval publication, such as the 
Anti-Submarine Bulletin, the COMINCH Bul- 
letins on AA or Amphibious Actions, or the 
Fleet Training publications embodying official 
doctrine. 

Any ORG manuscript was required to have 
the approval of at least one subgroup super- 
visor before being shown to anyone outside the 
group, and it had to have official approval by 
the appropriate naval officer before it received 
any distribution. 

The present chapter will take up in detail 
a few of the more important research prob- 
lems studied by ASWORG. The problems dis- 
cussed have been chosen so as to be more or 
less typical of the various aspects of the work 
and so as to illustrate methods of solution and 
degree of success. The discussion covers only a 
small part of the work accomplished, but it is 
felt that a better picture can be given by going 
into detail on some parts, rather than attempt- 
ing to outline the whole. 


72 THE SEARCH PROBLEM 

The problem of determining the proper meth- 
ods of search for submarines and other craft 
has demanded the expenditure of a fair per- 
centage of the energy of Group M since its be- 
ginning. The problem in all its ramifications 
enters into more than half of the antisubmarine 
tactics and into a great deal of naval tactics in 
other fields. The ocean is wide, and it is impos- 
sible to watch all parts of it all the time. Con- 
sequently, it is necessary to devise methods to 
determine the enemy’s location from time to 
time, and means of estimating the efficiency of 
the methods. Special cases also arise that re- 
quire plans for locating and apprehending all 


enemy craft trying to enter certain special 
regions of the ocean. Under these circum- 
stances the problem is to determine the most 
effective course for the patrol craft, and to com- 
pute their chance of locating the enemy. 

The determination of the best placement of 
escorts about a convoy is essentially a search 
problem, as is also the devising of barrier pa- 
trols to keep U-boats from going through speci- 
fied passages such as the Straits of Gibraltar. 
The determination of the best course to be fol- 
lowed by a destroyer in trying to make sound 
contact on a submarine which has been forced 
down by aircraft is an application of general 
search principles; the proper combination of 
radar and nonradar flying against submarines 
which have radar search receivers is another 
complicated application. 

One of the first tasks of Group M, in April 
1942, was to set up the general mathematical 
principles of search and to define the various 
quantities which would have to be studied 
analytically and statistically. Memorandum 
No. 1 contains most of these definitions. 


Range and Search Rate 

In the first place there is the range of detec- 
tion, by eye, by radar, or by sonar gear. The 
simplest assumption was made first; namely, 
that nothing was detected outside this range 
and everything was detected which came within 
the range. A ship, then, would have a definite 
sound detection range, which might vary from 
day to day, but which was definite in length 
for a given case. A nonradar plane would have 
a definite visual range for sighting ships which 
would vary with altitude and, of course, with 
meteorological visibility. Similarly a radar set 
on a plane or surface vessel would have a defi- 
nite range on surfaced submarines. 

More important than the range is the search 
rate, the rate at which a craft with its detec- 
tion gear can search over the ocean for the 
enemy submarine or surface vessel. A measure 
of this rate is the number of square miles which 
a given craft can search in an hour. For the 
first crude results it was assumed that this was 
equal to the speed of the craft multiplied by 


THE SEARCH PROBLEM 


99 


twice the range of detection for the gear in 
question. 

The search rate varies widely from craft to 
craft, and its value indicates some of the ad- 
vantages and limitations of the particular craft 
and detection gear. For instance, an aircraft 
with visual or radar search has a search rate 
against surfaced submarines of about 1,000 
square miles an hour or more, whereas a surface 
craft with radar has a search rate of only 100 
square miles an hour. On the other hand, the 
search rate for aircraft against submerged 
submarines is practically zero, but the search 
rate for surface vessels with echo-ranging gear 
is approximately 10 square miles per hour. Con- 
sequently, it is comparatively easy for an air- 
plane to find a surfaced submarine, but it re- 
quires nearly one hundred times the effort for 
the surface craft to locate this same submarine 
after it has submerged. Of course, this is an 
oversimplified picture of a very complicated 
problem. 

It was soon recognized that the simple as- 
sumption of a sharply limited search range, 
within which all objects were detected and out- 
side of which no detection was possible, was a 
very crude approximation. Actually some sur- 
faced submarines are seen at great distances 
by aircraft, for instance, and others under the 
same conditions are not seen until close in. 
Therefore, a more careful study of the search 
problem required the calculation of the proba- 
bility that the submarine is seen at a given 
range. From this probability one can then com- 
pute the average range under certain condi- 
tions, and one can also compute the effective 
search rate; a little consideration shows that 
the effective search rate is not necessarily equal 
to the speed of the craft multiplied by twice 
the average search range. 


Comparison with Operations 

Some operational data was available for 
study — enough to indicate the nature of the 
problem. Reports of aircraft attacks on sub- 
marines usually included values of the range of 
first contact, and the nature of the contact 
(visual, radar, etc.). These data were being 


punched on IBM cards, and could be analyzed 
by machine methods. The results showed a wide 
variation of ranges of first sighting, as men- 
tioned above. 

It was hoped that empirical curves for the 
probability of sighting could be computed from 
these data, but several difficulties arose. Since 
the chances of sighting would differ for differ- 
ent elevations of the plane and for different 
meteorological visibilities, the data would have 
to be separated into groups according to eleva- 
tion and visibility before analyzing. However, 
many reports did not give both elevation and 
visibility, and the reports which did were not 
numerous enough to provide a solid basis for 
the computations. Another difficulty was more 
basic: these reports were of sightings which 
resulted in attacks, and there were no corre- 
sponding reports sent in on sightings not re- 
sulting in attacks. There was reason to believe 
that these latter sightings were often the long- 
range sightings (where plane and U-boat both 
saw each other at a great distance and the 
U-boat submerged before the plane could at- 
tack). At any rate, it was probable that the 
attack data did not represent an unbiased 
sample of all sightings, so that sighting proba- 
bilities computed from this source would be 
open to suspicion. A well-reported sample of 
all sightings was needed. 

The effective search rate could sometimes be 
obtained from other operational data. In some 
parts of the ocean it was possible to estimate 
with reasonable accuracy the number of sub- 
marines present at a given time. By estimating 
also the submergence tactics of the submarines, 
one could thus estimate the average number of 
submarines which could be sighted by planes in 
the area. If one knew the search rate of the 
planes and the number of hours of flying in that 
area, one could compute the sightings to be ex- 
pected. Conversely, knowing the sightings and 
the hours flown, one could compute the effec- 
tive search rate. 

From the Eastern Sea Frontier and from the 
Biscay area, data were obtained giving the 
total number of hours flown and the total num- 
ber of sightings (of all sorts) obtained. From 
this, an effective search rate was obtained for 
each of the areas. This effective search rate 


100 


RESEARCH ACTIVITIES 


turned out to be from one-third to one-twen- 
tieth of that computed by using the average 
range of vision and the speed of the plane. The 
factor of discrepancy was too large to be ex- 
plained entirely by an error in estimating the 
number of submarines or their submergence 
tactics. Part of the factor could be explained 
by inefficiency in our own search tactics (over- 
flying, etc., to be discussed later) , but part had 
to be due to the fact that many submarines 
which “should” have been seen were not seen. 
The quantitative answer could not be given, 
however, until more complete data on sightings 
were available. Until the complete answer was 
obtained, one could never be sure how “tight” 
various barrier patrol plans actually were. 

ASWORG never did get a large enough and 
statistically-unbiased enough sample of aircraft 
visual sightings of submarines from American 
operational forces to make this analysis. At the 
time when U-boat sightings were coming thick 
and fast, the procedure for reporting sightings 
was not in effective operation ; and, even later, 
there was a natural indisposition to report con- 
tacts which did not lead to attacks. 

Luckily, adequate data could be obtained 
from England. In the Bay of Biscay the sight- 
ings were quite regular in occurrence, since 
there was a constant stream of U-boats coming 
in and out of the French ports. The antisub- 
marine air bases in England were fairly close 
together, so that all could be visited and their 
original records of sightings studied. Coastal 
Command consented to allow Dr. Kip, an 
ASWORG member assigned to London, to make 
this study. A sample of 529 sightings with all 
the pertinent data concerning altitude of plane, 
meteorological visibility, range and bearing of 
first sighting, etc., were collected and sent to 
the Washington office. There the material was 
put on IBM punch cards and analyzed statis- 
tically by Dr. Kimball, who has been respon- 
sible for much of the theoretical development in 
this field. 


Sighting Probability Curve 

The first results of the statistical analysis 
showed that the average range of first sighting 


was proportional to the meteorological visibility 
and also proportional to the square root of the 
elevation of the aircraft at the time of sight- 
ing. These two relationships were to be ex- 
pected, but it was gratifying to find the opera- 
tional data checking the expectation. A range 
parameter could then be defined which was 
equal to the range of the first sighting divided 
by the meteorological visibility and by the 
square root of the elevation. One could then ob- 
tain from the data a plot of the probability of 
first sighting against this range parameter 
which was the needed sighting probability 
curve, the basis for all further work in air 
search plans. The scanty American data was 
also checked with this probability curve, and 
shown not to disagree. 

On the basis of this sighting curve, obtained 
from operational data, different aircraft search 
plans could be compared in efficiency, and the 
best plan found. The plans resulting from this 
work have been incorporated in Fleet Tactical 
Publication 223 (FTP223), the official U. S. 
antisubmarine doctrine. 

The basic sighting probability curve ob- 
tained in this manner was an empirical one. 
One further step was needed before the em- 
pirical data could be satisfactorily linked with 
fundamental theory, namely, the connecting of 
the empirical curve with the physiological 
properties of the human eye, for visual search. 
This step was taken by Dr. E. S. Lamar, who 
had worked with Dr. Kimball in the empirical 
analysis of the sighting data. Shortly after this 
analysis had been finished, Dr. Lamar was sent 
to the London office and discussed the interpre- 
tation of the British data with the members of 
ORS/CC. With their help he was able to obtain 
physiological data, from the measurements of 
Craik and MacPherson of the British Medical 
Research Council, which enabled the last step 
to be taken. (It is curious that in this work on 
visibility and search nearly all the data came 
from England and nearly all the theoretical 
analysis and application to tactics was made 
in Washington.) Further work on this basic 
problem has more recently been carried on by 
Dr. Lamar in cooperation with Prof. Selig 
Hecht of Columbia University. 

These measurements on visibility showed 


THE SEARCH PROBLEM 


101 


that there was a certain maximum range of 
vision for any given object, which depends on 
the apparent size of the object and on the 
brightness contrast between the object and its 
background. The brightness contrast depends 
directly on the meteorological visibility, since 
distance reduces the contrast, particularly on a 
hazy day. The apparent size (solid angle sub- 
tended) of the object depends on the altitude 
of flying if the object is flat on the surface of 
the water as is a U-boat wake. The final result 
is a rather complicated relationship between 
maximum range and visibility and altitude. For 
objects of intermediate size and for reasonable 
visibilities, this relationship reduces to a simple 
product (visibility times square root of alti- 
tude) which the empirical data had shown. 
Moreover, the theoretical constants check the 
operational data. 

The more complete theory, however, has en- 
abled the basic range probability curve to be 
extended to much smaller sized objects, such as 
life rafts and periscopes. Its application to 
other problems in surface vessel and aircraft 
tactics may also be quite useful, as for instance 
in the study of the efficacy of lookouts on our 
submarines in spotting enemy aircraft, and in 
the determination of the usefulness of various 
types of camouflage. Consequently one can say 
now that the fundamental problem of the visual 
search for, and sighting of, an object on the 
ocean from an airplane (or vice versa) has 
been solved in its main aspects, if not in all de- 
tails. 

The corresponding fundamental problem for 
radar sightings from aircraft is not in quite so 
satisfactory a state, primarily because of the 
insufficiency of data. The general operational 
behavior of the radar set is fairly well known, 
however, and the general shape of the proba- 
bility curve for radar sightings is known suffi- 
ciently well to enable radar search plans to be 
laid out. Some fundamental questions, however, 
have not yet been answered. 


Barrier Patrols 

The fundamental studies of visual, radar, 
sonar, and MAD detection have been primarily 


useful as a foundation for the study of the 
more immediate problem of devising search 
procedure. In this more practical field also, the 
simplest problems were tackled first and the 
more complicated ones were only attempted 
after experience and basic knowledge had been 
gained. 

The simplest practical search problem is that 
of the barrier patrol, a patrol designed to de- 
tect “every” enemy vessel which tries to enter 
a certain part of the ocean. The patrol course 
is retraced periodically, and for the barrier to 
be tight the strip of ocean searched out must be 
wide enough and the patrol craft must return 
often enough so that the enemy vessel cannot 
cross the search strip before the patrol craft 
returns. Certain geometrical considerations, 
due to the fact that the enemy vessel is usually 
traveling across the path of the patrol craft, 
require modifications in the shape of the patrol 
courses in order to obtain the greatest efficiency 
for the barrier. All this was set down in a 
number of articles written by ASWORG, and 
published in the U. S. Fleet Anti-Submarine 
Bulletin. 

Several interesting applications of simple 
barrier patrols were devised by ASWORG 
base members to meet specific local operational 
needs. Pellam, while at Moroccan sea frontier, 
assisted in the devising of an MAD barrier pa- 
trol for the Straits of Gibraltar, against sub- 
marines coming into the Mediterranean. This 
barrier was carefully placed with respect to the 
deep channel through the Straits and with 
respect to the other antisubmarine patrol craft 
and planes. The patrol was first tried in Jan- 
uary 1944, and resulted in the certain sink- 
ing of one submarine and the almost certain 
sinking of two more submarines within the 
first 4 months. The continuation of the com- 
bined barrier effectively stopped submarine 
transit into the Mediterranean from that time 
on. 

Dr. Steinhardt assisted officers of the Fourth 
Fleet to lay out a barrier patrol on a much 
larger scale, to intercept German surface vessel 
blockade runners returning with important sup- 
plies from Japan. Planes were flown back and 
forth along carefully laid-out courses from 
Brazil to Ascension Island at a frequency suf- 


102 


RESEARCH ACTIVITIES 


ficient to provide a barrier patrol. Three of the 
four runners were caught by this patrol; it 
was found later that the fourth had passed 
through before the barrier had been set up. 


Convoy Escort Plans 

The aircraft escort of convoys constitutes a 
type of barrier patrol, for the basic require- 
ment is that the planes are to sight all surfaced 
submarines well before they might reach the 
convoy. Plans for convoys and planes of vari- 
ous speeds were devised by ASWORG as early 
as May 1942, as the need for proper convoy cov- 
erage doctrine was urgent then. Since the group 
was inexperienced at that time, there was con- 
siderable doubt as to whether the plans which 
had been devised theoretically were likely to 
be effective in practice, and even whether they 
could be flown. Shortly after Dr. Rinehart had 
been assigned to the Caribbean sea frontier he 
obtained permission to test the escort plans 
which he had had a large part in devising. This 
practical test suggested certain minor modifi- 
cations, and after very considerable discussion 
with many antisubmarine fliers, a final set of 
escort plans was drawn up. These still provide 
the basis for aerial escort doctrine, and are 
published in U. S. Fleet FTP223. The area cov- 
ered by the escort plan naturally depends on the 
effective ranges of visibility of the plane for 
visual or radar sighting of a surfaced subma- 
rine. These are obtained from the fundamental 
sighting curve mentioned in Section 7.2.3. 

A training film, in the form of an animated 
cartoon, illustrating the merits of the plans, was 
produced for distribution to the operating 
forces. J. L. Little, a group member, assisted 
in its preparation. 

A large number of special plans for the pro- 
tection of various task forces in the Pacific were 
worked out in response to requests from vari- 
ous Fleet Commands. 


Hunt Plans 

The next type of search plan studied was the 
hunt. A submarine is contacted either by a 


sighting (visual, radar, etc.) or as a result of 
an attack on a surface vessel ; and the problem 
is to find the U-boat (which usually submerges 
when it realizes it is being hunted) before it 
escapes completely. 

This problem is obviously much more com- 
plicated than is the barrier patrol problem, 
even if the hunt is carried on entirely by air- 
craft; for here one must take into account the 
actions of the submarine in a more detailed 
manner. The simplest way, of course, is to send 
out enough planes so that the whole area, within 
which the submarine must be, is kept under 
continual observation. Naturally the hunt must 
last long enough so that the submarine 
will have to surface and will thus be caught. 
This is called the hunt to exhaustion and rep- 
resents the least amount of cleverness and the 
greatest amount of effort on the part of the 
hunter. 

A great many hunts to exhaustion were tried 
in 1942 and 1943, and nearly all of them failed. 
Group M was assigned to find out why they 
failed and to devise better hunt plans. Group 
members were sent to the various air bases 
which had conducted the hunts and obtained 
complete details concerning the flying involved, 
both as to location and time. It soon became 
apparent that none of the so-called hunts to 
exhaustion involved a sufficiently continuous 
search of enough of the ocean to insure the 
spotting of the resurfacing submarine. In all 
cases there were enough “holes” in the flying 
to allow an escape. Such a hunt needed to be 
continued for about 3 days, over an ever widen- 
ing area, and almost always, in practice, bad 
weather intervened, or planes suffered some mis- 
hap, or other duties interfered. It became clear 
that such hunts exhausted the hunter before 
they exhausted the prey. The problem, there- 
fore, was to devise a means of utilizing air- 
craft that would have a reasonable chance of 
success without using an unreasonable amount 
of flying effort to regain contact with the sub- 
marine. 

A number of attempts were made on this 
problem, with varying degrees of success. 
Nearly every ASWORG member assigned to 
an operating base was asked by the operations 
officer from time to time to suggest hunt plans 


THE SEARCH PROBLEM 


103 


when the need arose. Thus an empirical body of 
knowledge grew up as to what plans seemed to 
succeed and what plans did not. In order to 
speed up this experience, a battle game was de- 
vised by members in the Washington office 
where one of the members took the part of the 
escaping submarine and another the part of the 
plane. Equipment was built by the Special De- 
vices Section of the Bureau of Aeronautics to 
simulate the search range of the plane and the 
range of visibility of a submarine at periscope 
depth and when fully surfaced. It was discov- 
ered that a great many hunt plans were in- 
effective because the submarine had a chance 
to observe the patrol plane through its peri- 
scope for several patrol cycles before it needed 
to resurface. By this sequence of observations 
the submarine would learn how to time its es- 
cape. 


7 ' 2 ' 7 Gambit and Convoy Escort Carrier 
Plans 

One way of avoiding this difficulty had al- 
ready been suggested. This was a plan that 
ultimately came to be called the gambit and 
which consisted of flying the aircraft in a 
course which would be out of visual range of 
the submarine as long as it stayed at periscope 
depth. This would lead the submarine person- 
nel to believe that the planes had been with- 
drawn and would induce them to surface. Once 
the U-boat had been surfaced, it would cross 
the path of the patrolling plane if it tried to 
escape at high speed and would presumably 
present another opportunity for attack. De- 
tailed plans were devised to obtain the best 
chance of recontact. 

Gambit plans were used in hunts in a num- 
ber of frontiers and were successful in pro- 
ducing recontacts. Such plans usually have to 
be made up on the spot to fit the particular 
situation at hand. ASWORG members at Gulf 
sea frontier, Caribbean sea frontier, Brazil, 
and Moroccan sea frontier contributed from 
time to time in the laying out of hunts after a 
submarine had been spotted. 

Combinations of hunts and barrier patrols 
are flown from convoy escort carriers [CVE] 


and much analytical work was done in devis- 
ing plans for their use. The carriers used planes 
having characteristics other than those of the 
usual land-based antisubmarine planes, and 
consequently, modifications of the usual escort- 
of-convoy plans were prepared. Carriers of this 
type turned out to be most useful as offensive 
weapons by searching out and sinking U-boats 
rather than waiting for the submarine to come 
to the convoy. A large number of CVE search 
plans for different situations were devised and 
proposed for operational use. Others submitted 
by commanding officers were evaluated. 

Still different situations turned up when the 
carrier planes began night flying, and when 
various types of microwave radar equipment 
began to be installed ; so other plans were 
worked out. Close relations were maintained 
with many carrier officers, particularly with 
the air combat intelligence and antisubmarine 
officers, who had the prime responsibility in 
laying out hunt plans during a voyage. Several 
of these officers visited the Washington 
ASWORG office and discussed various prob- 
lems of search and tactics. 


Surface Vessel Search Plans 

The surface vessel search problem is more 
difficult than the aircraft case in that the speed 
of the surface vessel is not large compared to 
the speed of the U-boat. Consequently, the eva- 
sive tactics of the submarine affect the search 
plans very strongly. This disadvantage is off- 
set to some extent by the fact that surface 
vessels can stay continuously on the spot, and 
can cooperate more closely in a hunt than can 
aircraft. It turns out, for instance, that three 
destroyers hunting in a line abreast are more 
than three times as effective as one destroyer 
hunting. 

An important property of the surface craft, 
of course, is its ability to locate the submarine 
after it has submerged. Consequently, the fun- 
damental theory of visibility here concerns 
the operational behavior of echo-ranging gear. 
This problem was studied in great detail by 
Dr. W. C. Herring and others of the Program 
Analysis Group of Division 6, NDRC. From 


104 


RESEARCH ACTIVITIES 


their work it is possible to determine the 
probability of locating a submerged submarine 
by a surface vessel under various conditions. 

A situation often encountered was that in 
which one or more destroyers were called on 
the scene by an aircraft which had made an 
initial sighting and had forced the submarine 
to submerge. The destroyers arrived on the 
scene one or more hours later and then the 
problem was to devise a search plan for the 
destroyers to locate the submarine as soon as 
possible. The same condition obtains when con- 
tact has been made and subsequently lost by 
surface craft. Because of the relative slowness 
of the destroyers, it appears that some form 
of search course which spirals out from the 
contact point is usually the best course (this is 
known as the retiring search curve). The rate 
of retirement and the spacing of ships in line, 
if there are more than one hunting, were mat- 
ters for analysis. Various types of plans were 
laid out, the probability of the submarine’s es- 
cape being computed for each plan, and the best 
plan was chosen. Like the plans for aircraft, 
search plans for surface vessels devised by the 
ASWORG office were incorporated in FTP223. 

Additional complications are added when 
aircraft are available, as with a carrier task 
force. The aircraft can be used on a gambit 
hunt, for instance, outside the expanding spiral 
of the surface vessels. If the submarine should 
escape the vessels and try to depart at high 
speed on the surface, the aircraft has a chance 
of intercepting it. 

Each new means of detection or new modifi- 
cation of detection gear has required modifica- 
tion of these various search plans in some way 
or other. For instance, the introduction of the 
use of sono buoys by aircraft has enabled the 
aircraft to keep track of submerged submarines 
to some extent. This made it possible for the 
aircraft to keep a certain amount of contact 
with the submarine after it was forced below, 
and to call destroyers to it from farther away 
than was previously considered worth while. 
Even if the destroyers arrived on the scene 
several hours later, it was possible for the air- 
craft still to be in tenuous contact with the 
submarine. In such cases, extensions of the 
fundamental theory were worked out and each 


of the standard search plans was investigated 
to see if it should be modified. 

Thus it is seen that the applications of fun- 
damental sighting theory are endless. Other 
applications, as World War II drew near an 
end, were being worked on. These included 
search plans to rescue air crews forced down and 
screens to protect large task forces from sub- 
marines and aircraft. An exceedingly important 
study undertaken in the war’s closing months 
involved the re-evaluation of all surface and 
air search plans to take into account the U-boat 
use of Schnorchel. 


7 3 STATISTICAL ANALYSIS USING 
PUNCH CARDS 

Most of the statistical work carried on by 
ASWORG involved the abstracting of various 
details of operations from some standard naval 
report form. In many cases the report forms 
had been devised before ASWORG came into 
existence, and the abstracting of data was al- 
ready being done by some parts of the 
COMINCH staff so that ASWORG members 
took the abstracted data as the basis for their 
statistical studies. In other cases the report 
forms had been devised and reports were com- 
ing in that had not yet been abstracted; in 
some of these cases ASWORG members did the 
abstracting as well as the statistical analysis. 
In a few cases, ASWORG members assisted in 
the devising of the report form as well as in 
the abstracting and the analysis. In all these 
cases the IBM equipment played a useful role. 

The abstracted data from operations reports 
were used in two different ways. In the first 
place, the data could be tabulated in an easy- 
to-read situation summary, to provide the 
higher command with an up-to-date picture of 
the status of a given operation. In the second 
place, the data was combined with other facts 
to provide a measure of efficiency for a given 
operation, which might be watched from month 
to month in order to determine the best tactics 
for an operation, or to find how much the effi- 
ciency of an operation improved as experience 
was gained, or to determine whether changes 
in enemy tactics had a deleterious effect on the 


STATISTICAL ANALYSIS USING PUNCH CARDS 


105 


efficiency of our own operations. (The effective 
search rate, computed from sighting reports, 
is an example of a measure of efficiency.) Group 
M members were of assistance in producing 
some situation summaries; they took a more 
active part in setting up and following various 
measures of efficiency of operations. 

Since the beginning of World War II the 
abstracting of data from antisubmarine action 
reports and the preparation of situation sum- 
maries came under the cognizance of Com- 
mander (later Captain) R. F. Collins (FX-43). 
Group M went to him for data as soon as they 
had become established in Washington, and it 
was his understanding cooperation which saved 
the group from making many false starts. Cap- 
tain Collins’ office maintained records of Allied 
shipping sunk or damaged, and a similar de- 
tailed record of attacks on enemy submarines, 
all of which were constantly revised and kept 
up to date. This material formed the basis of 
daily situation summaries prepared by Cap- 
tain Collins and it also formed the basis of a 
great number of statistical studies made by 
ASWORG. After working with this material 
for several months, it was agreed that the 
needs of both Captain Collins’ office and of 
Group M could be met most efficiently by an 
IBM machine installation. Later the action re- 
ports on other types of naval operations were 
coded for the other subgroups. Patrol reports 
of our submarines and AA action reports were 
thus transcribed for detailed analysis and study. 


Punch Cards 

The basis of the IBM installation was the 
punch card, a small cardboard ruled with 80 
columns, each having 12 spaces, any of which 
could be punched. Essentially, therefore, each 
card could carry an 80-digit number or an 
80-letter sentence, since each column stands 
either for a digit or a letter. By coding the 
sort of data which were to be reported, a great 
number of facts could be put on a single card. 
For instance, in recording ship sinkings, the 
first 16 columns gave the name of the ship 
which sank, the next 2 columns the code letters 
for the nationality. One column gave the code 


letter for the type of ship, the next 5 columns 
the tonnage, followed by 4 columns giving the 
date, 9 columns giving the latitude and longi- 
tude, and so on. These cards could be sorted 
according to any of the columns and therefore 
could be put in order of date, in order of ton- 
nage, or any other order which was wished. 
Columns were read off in another machine, the 
tabulator, and, for instance, totaled in order 
to give the total tonnage sunk in a day or a 
month. The tabulator also would print data 
from properly ordered cards, automatically 
producing a situation summary. By proper or- 
ganization of these various machines, a large 
variety of different operations could be carried 
out, thus reducing enormously the labor of 
statistical analysis. 

A card punch and verifier, together with a 
sorter, interpreter, and small tabulator, were 
ordered and were finally delivered in December 
1942. These machines were set up in a room 
next to Captain Collins’ office. Later, in Novem- 
ber 1943, additional equipment was obtained. A 
full-sized tabulator replaced the small one, and 
a more modern verifier replaced the old type. 
A reproducing summary machine and a card 
counting sorter were also added. 


Design of Codes 

Even before the first equipment had been 
delivered, preparatory work was under way for 
placing the data on the cards. A most important 
part of the use of punch cards is the working 
out of the code which specifies the order and 
arrangement of the data on the card. Decisions 
on the make-up of the code are extremely im- 
portant, since a badly designed code can make 
a number of statistical investigations almost 
impossible. Codes which are best for calcu- 
lating measures of efficiency are not necessarily 
good for producing situation summaries and 
vice versa. Since it is quite difficult to change 
the code after the system has been in operation 
for some time, it is important that all future 
contingencies be thought of when the code is 
made out. Professor Wilks was of considerable 
help in this respect, and the details were ably 
handled by W. L. DeVries, H. H. Hennington, 


106 


RESEARCH ACTIVITIES 


and P. J. McCarthy, and later by R. R. Seeber, 
who had been engaged to supervise the actual 
operation of the machines. The first cards were 
set up and punched, and a number of runs were 
made, utilizing IBM machines at Princeton 
University. By the time, therefore, that the 
ASWORG machines were delivered, the basic 
codes were pretty well arranged. 

An agreement was made with Captain Col- 
lins whereby the time of the machines and the 
supervisor was used by Captain Collins each 
afternoon for his special tabulations and other 
work; the morning was made available for 
ASWORG work. This arrangement turned out 
to be quite satisfactory. Two WAVE specialists 
were obtained to handle the punching of the 
cards and other mechanical details. By the 
spring of 1943 it was necessary to obtain the 
services of one other supervisor, Earl Gardner, 
and by the end of 1943 an additional WAVE 
assistant was obtained. 


733 Card Files Used 

i" 

A large number of card files of operational 
data were kept in the machine room available 
for tabulation of situation summaries or for 
statistical work. Some of those, prepared by 
Captain Collins’ office, of particular interest to 
ASWORG, comprised the Ship Casualty File, 
the World Wide Assessment Files, and the File 
of Details on Attacks on Enemy Submarines. 
The Ship Casualty Files had reached 3,500 
cards by August 1943 and 6,000 cards by 
August 1944. The World Wide Assessment 
Files, giving the overall facts on attacks on 
enemy submarines by any Allied craft, con- 
tained 2,500 cards in August 1943 and 5,000 
cards in August 1944. Both of these files were 
primarily designed for situation summary tab- 
ulations, but a great deal of general statistical 
information was also obtained from them. A 
more detailed file of attacks on enemy subma- 
rines by U. S. surface and aircraft gave a great 
deal of technical information about the attack 
and was of the utmost importance to ASWORG 
in working up measures of efficiency. This file 
reached the size of 8,000 cards by August 1944. 
Other files giving details on convoys, for in- 


stance, were of less use to Group M. All these 
files were controlled by Captain Collins, and 
ASWORG obtained permission from Tenth 
Fleet to utilize them in making its studies. 

As Group M expanded its activities, other 
card files came into existence. For instance, be- 
ginning in October 1943, a file was kept on the 
action reports of our own submarines in the 
Pacific and contained about 10,000 cards by 
August 1944. Similarly a file was maintained 
on air actions in the Pacific for Op-16-V-A 
(Air Intelligence Group) for statistical studies 
on air operations. This file was begun in Feb- 
ruary 1944, and reached a size of 8,000 cards 
by August 1944. At the beginning of its sta- 
tistical work, ASWORG felt that it was impor- 
tant to obtain approximate values for a large 
number of measures of efficiency for various 
antisubmarine operations. Until approximate 
operational values of these measures were de- 
termined, the group could not be said to know 
its subject in a quantitative manner. Data were 
therefore collected on a wide number of related 
facts and in many cases the results were re- 
ported regularly to the interested officers. Later 
it was found that some of these measures of 
efficiency remained practically constant and 
that others were unimportant in tactical stud- 
ies, so that only a few such measures were 
eventually continued. Nevertheless, many of 
them had to be tried at first. 


74 DATA ON FLYING 

An important measure of efficiency in the 
search problem is the effective search rate for 
aircraft. In order to obtain this from opera- 
tional data, one must count all the contacts on 
surfaced submarines by aircraft in a given 
area, and at the same time have records of all 
the flying time in that area spent in searching 
for submarines. If one is to compare different 
regions or different types of operation, the 
time spent in these regions or in these types of 
patrol (such as convoy or simple patrol or 
hunt) must be differentiated. If, in addition, 
the range of first sighting and other related 
data is reported, a good start is made toward 
learning the operational “facts of life” as far 


IMPORTANCE OF ASSESSMENTS 


107 


as search goes. Arrangements were made with 
the eastern sea frontier to obtain some of these 
basic data. 

Each plane on returning from an antisub- 
marine mission filled out a “form mike” which 
gave the details of the mission, the sightings, 
visibility, etc. Arrangements were made to have 
duplicates of all forms mike sent to the ASW 
unit, eastern sea frontier, where Group M 
members, aided by yeomen, tabulated the data 
and sent them to Washington to be put on 
punch cards. The data were at first recorded 
in great detail to see which parts were signifi- 
cant. Several interesting conclusions came from 
this study. One of the results was that the 
regions which had the greatest amount of pa- 
trol flying often gave the least number of sight- 
ings per hour flown by the planes. From these 
data one could determine the advantages and 
disadvantages of excessive amounts of patrol 
flying, and could estimate the amount of flying 
in a given region which would adequately pro- 
tect the region and would still give a number 
of sightings which could be converted into 
attacks. It was also found that flying some dis- 
tance from the shore (100 miles or more) was 
much more productive of sightings and attacks 
than flying closer than 50 miles from shore. 
It was also shown that the use of radar planes 
at night was a particularly effective method of 
obtaining sightings and, eventually, attacks, 
when proper searchlight equipment made night 
attacks possible. These results were embodied 
in reports to eastern sea frontier and had some 
effect on subsequent distribution of flying. 

A similar study of flying time and of opera- 
tional search rate was made for a time with 
data from Caribbean sea frontier. When this 
turned out to give the same general results as 
the eastern sea frontier data, both of the card 
files were discontinued, since it did not appear 
that further results of operational importance 
could be obtained and since the basic orders of 
magnitude of search rate had been determined. 

Another short-term card file was concerned 
with convoy statistics, whereby data on con- 
voys were analyzed for a long enough period 
to obtain the fundamental measures of effective- 
ness (relation of attacks on convoys to number 
of escorts and to speed of convoy, etc.). The 


file on Coastal Command Visual Sightings, men- 
tioned above in connection with the search 
problem, was another such short-term project. 

75 IMPORTANCE OF ASSESSMENTS 

In obtaining measures of, efficiency in attacks 
on submarines, the official assessments of the 
individual attacks had particular importance. 
As a matter of fact, the proper assessment of 
an action report is of extreme importance to 
nearly all operational research. If this research 
is to be of use in deciding the relative effective- 
ness of various types of tactics, it must know 
how effective the tactics are when actually 
tried. In many cases the results of the opera- 
tions are clearly apparent and the tabulation 
of the statements on the action reports suffices 
to obtain a measure of the effectiveness of the 
action. Cases of this sort were the reports of 
hours flown on patrol and the reports of sink- 
ings of vessels by U-boats. In both of these 
cases a reading of the details of the action 
report sufficed to give the research worker a 
fairly accurate picture as to what had happened 
and no careful assessment by a board of ex- 
perts was needed. 

In other cases, however, the results of the 
action are not at all apparent, and the action 
reports must be read by experts with a great 
deal of operational knowledge before arriving 
at a considered judgment of the result. A con- 
siderable amount of operational research of 
the statistical sort could not have been done 
in antisubmarine warfare if there had not been 
a Naval Assessment Committee for Antisub- 
marine Action. This committee graded attacks 
in a sequential order: A, being certainly sunk; 
B, being probably sunk, etc. ; down to G, attack 
probably on a submarine, no damage ; H, attack 
probably not on a submarine ; etc. The accuracy 
with which these assessments conformed to 
later discovered facts was astonishing and in- 
dicative of the experience and skill of the 
Assessment Committee. 

7 5,1 Studies of A/S Attacks 

These assessments of antisubmarine action 
enabled ASWORG to devise a measure of effi- 


108 


RESEARCH ACTIVITIES 


ciency for various types of attack and there- 
fore to compare the effectiveness of various 
attack tactics. Since numerical values are the 
most useful means of comparison, several dif- 
ferent weights for the assessment letters were 
tried, representing the relative probability that 
the U-boat was sunk; such as 1.0 for A, 0.8 
for B, and 0.5 for C. It was finally decided that 
the percentage of A and B assessments result- 
ing from a given type of attack was an ade- 
quate measure of effectiveness. 

With this measure as a tool, it was possible 
to study the attack cards provided by Captain 
Collins’ office to judge the efficacy of various 
antisubmarine tactics. Several interesting facts 
soon came to light. In studying the statistics 
of aircraft attacks, for instance, it was soon 
discovered that attacks made on submarines 
that had submerged more than 30 seconds be- 
fore the plane dropped its depth bombs were 
very unlikely of success. The results were strik- 
ing enough to warrant including in the air 
attack doctrine a phrase forbidding the drop- 
ping of depth charges on submarines which had 
been submerged more than 30 seconds. 

Another problem which received early study 
was the question of the depth setting of the 
depth bombs carried by aircraft. Early in the 
war the setting was usually 50 ft, which was 
too deep to be lethal to surfaced submarines. 
A statistical analysis of aircraft attacks on 
submarines showed that about half of the sub- 
marines were on the surface at the time of 
attack. This, combined with the fact that the 
attacks on submerged U-boats were much less 
accurate, indicated that the depth setting should 
be adjusted for lethality against the surfaced 
submarine. 

Consequently doctrine was modified to re- 
quire a 25-ft setting, and a memorandum was 
published explaining the reasons. A later com- 
parison on assessments of attacks with the two 
settings showed that the change in depth set- 
ting was equivalent to a doubling of the effec- 
tive lethality of the depth bomb. 

7 6 OTHER PROBLEMS 

The IBM machinery was of use in analytic 
problems as well as in the collection and analy- 


sis of operational data. The probability of suc- 
cess in depth-charge patterns is a problem 
amenable to calculation by punch card meth- 
ods. A file of 7,500 cards, giving error distri- 
butions based on operational statistics, were 
punched so that all types of patterns could be 
studied. Many of the results of this study were 
incorporated in FTP223 as doctrine. In a sim- 
ilar manner a file of 7,000 cards was built up 
to compute the probability of success (and 
other details) for surface vessel search plans. 
In these cases the IBM machines were used as 
an extremely flexible computing machine. Since 
the card files can be kept, the problem can be 
returned to again if further work is needed. 

77 COUNTERMEASURES 

The work on the search problem discussed in 
Section 7.2 was mostly analytical. The work 
just discussed in the intermediate sections was 
primarily statistical. The work to be discussed 
in this section has had more to do with materiel, 
although it has had important analytical and 
statistical aspects. The work carried on by 
ASWORG in countermeasures in antisubma- 
rine operations had been primarily in two 
fields, radar and underwater sound, although 
the work is typical of operational research in 
countermeasures in other fields. The general 
problem was as follows. The enemy devises a 
new piece of equipment or tactic and seems to 
be in the process of introducing the equipment 
or perfecting the tactic ; it is required to devise 
equipment or tactics or both to counter the 
enemy’s innovation and to devise criteria to 
show when these countermethods need to be 
introduced by our forces. The question of tim- 
ing the introduction of the countermeasure 
often turns out to be as important as the 
devising of the countermeasure itself. There is 
also the problem of foreseeing possible enemy 
countermeasures to new equipment or tactics 
of our own. 

Countermeasures in the Bay 
of Biscay 

The radar countermeasure problem in anti- 
submarine warfare has a longer history than 


COUNTERMEASURES 


109 


the acoustic case and provides more examples 
of Group M activities. In order to obtain a 
picture of the interplay of events in this field, 
it is useful to outline the history of the air 
offensive carried out by Coastal Command 
against U-boats in the Bay of Biscay. In the 
early part of the activity, most of the sightings 
were made by visual means. Flying was done 
nearly all in the daytime, and the number of 
sightings and attacks on U-boats had settled 
down to a relatively constant percentage, which 
evidently was not large enough seriously to 
disturb the enemy. In June 1942, however, 
Coastal Command outfitted a number of squad- 
rons of planes with both long-wave radar sets 
and searchlights, so that they could find sur- 
faced submarines at night and could carry out 
attacks against them. The night flying was 
arduous and the effectiveness of the night at- 
tacks was not too high, but the psychological 
effect more than made up for this. Previously 
the submarine had been relatively immune in 
the Bay of Biscay at night, and it was cus- 
tomary practice to travel all night on the sur- 
face. The first reaction of the enemy to search- 
light radar planes was to reverse their time 
table, to stay submerged at night and to come 
to the surface by day. By September 1942, the 
searchlight planes were making very few at- 
tacks but the number of attacks made by day- 
flying planes in the Bay had risen considerably. 
Therefore the night flying of two squadrons 
had increased the effectiveness of more than 
seven squadrons of day-flying planes. 

This increase evidently was too much for the 
enemy. Within four months after night flying 
commenced, he had installed search receivers 
for long-wave radar sets on the majority of his 
submarines. These receivers picked up the sig- 
nals from the long-wave radar sets on the 
planes and warned the submarine in time for 
it to submerge and escape. Evidence of the 
installation of these receivers was furnished 
by an increase in the number of “disappearing 
contacts,” radar contacts which disappeared 
before the plane obtained visual confirmation 
of the presence of the submarine. Only a small 
percentage of disappearing contacts corre- 
sponded to submarines with search receivers, 
but the increase in disappearing contacts cor- 


roborated other evidence that search receivers 
were being installed. 

By November 1942, the searchlight planes 
with long-wave radar had been effectively coun- 
tered by the German search receiver. The sub- 
marines had gone back to surfacing at night, 
only diving when their receiver warned of a 
plane’s approach. The number of attacks at 
daytime had subsided to its previous level, and 
equilibrium appeared to rule again. 

The introduction of S-band radar on the 
British night-flying planes upset this equilib- 
rium all over again. The German search re- 
ceivers were not designed to pick up the shorter 
wavelength, and therefore the number of sight- 
ings and attacks by night-flying planes rose 
rapidly. The cycle went through its previous 
course, the Germans first submerging by night 
and surfacing by day with a resulting increase 
in day sightings and attacks. Next, they rushed 
a search receiver for the short-wave radar. 
This proved somewhat more difficult to install 
but eventually a semblance of equilibrium was 
again reached by October 1943. 

This sequence of events was duplicated with 
some variations on this side of the Atlantic. 
The variations in the sequence were the special 
object of study by ASWORG. The Bay of Bis- 
cay constituted a special field of activity, and 
it is important to realize that tactics differed 
in other localities. Much of the activities of 
ASWORG in the radar countermeasure field 
were engaged in showing wherein the problem 
for American waters differed from the problem 
in the Bay of Biscay and in suggesting the 
modifications in tactics and gear required by 
these differences. 


Materiel Countermeasures 

The difference between the attitude of a de- 
velopment laboratory and the attitude of an op- 
erations research group toward a countermeas- 
ure problem is an interesting and important 
one. Since it takes time to develop and produce 
equipment, the development laboratory must 
think up and work out countermeasure equip- 
ment for every imagined type of enemy gear 
in the hope that the right one will be “on the 


110 


RESEARCH ACTIVITIES 


shelf” when the enemy comes out with his next 
measure. Thus in the antisubmarine radar field, 
the development laboratories had to anticipate 
that the Germans would either use aircraft 
warning radar on their submarines or else 
would use search receivers, and equipment had 
to be devised for both. The proper counter- 
measure for an early warning radar on a sub- 
marine is a search receiver on our own aircraft. 
Receivers of this sort were devised by NRL and 
by Division 15, NDRC, and were procured by 
the Bureau of Ships. 

Equipment countermeasures to a German 
search receiver were more difficult, but one, 
the Vixen, was devised. This was simply an 
attenuator in the aircraft radar set which 
would gradually reduce the strength of signal 
after the aircraft had picked up a suspicious 
contact. This attenuation would allow the sig- 
nal strength received by the submarine to stay 
constant or even diminish as the aircraft ap- 
proached, while still maintaining a visible spot 
on the radar screen. By this means it was 
hoped the receiving operator on the submarine 
would be fooled into believing the aircraft was 
not approaching, for if the receiver were not 
sensitive the signal might not be detected at all. 
Equipment of this sort was developed by Divi- 
sion 14, NDRC. 

The problem for ASWORG, however, was to 
decide which of the tactics the Germans were 
adopting and when the appropriate counter- 
measure gear should be installed in our own 
planes. Most countermeasure gear and tactics 
involve a loss in efficiency in other ways, so that 
it was important not to commence counter- 
measures until the Germans had installed gear 
which required countering on a sufficient num- 
ber of submarines. For instance it was partic- 
ularly important not to advise tactics counter- 
ing German radar if the Germans actually were 
installing search receivers or vice versa. 

X-Ray Plane 

Partly at the suggestion of Group M, a plane 
equipped with a number of radar search re- 
ceivers was sent to North Africa to fly in 
waters known to be frequented by submarines. 
A three months’ stay involving a large amount 
of flying both by day and by night produced 


no recognizable radar signals from submarines 
and showed, with reasonable certainty, that 
radar was not being used by U-boats for air- 
craft warning. 

The problem of the degree of U-boat use of 
a search receiver was a much more difficult one 
to solve. The solution depended on the balancing 
of advantages. If the German search receiver 
came to have a long enough range and was 
effective enough of the time, on enough sub- 
marines, then it might be advantageous to turn 
off our antisubmarine radar and go back to 
visual search. On the other hand, if the receiver 
range was relatively short or if the receiver 
was often out of adjustment or was not present 
on many submarines, then turning off our own 
radar would be a grave mistake and would lead 
to a considerable reduction in the number of 
successful attacks. In order to reach a decision, 
data from a number of different sources had to 
be carefully balanced. 

Disappeaking Contacts 

In the first place, there was the operational 
data which came mainly from reports on dis- 
appearing contacts. These data had to be viewed 
with a great deal of skepticism. Even a large 
increase in the total number of disappearing 
contacts in a given region might not indicate 
that the U-boat was using search receivers in 
that region. It might only mean that the anti- 
submarine squadrons in that region had sud- 
denly become upset about the possibility of the 
U-boats having search receivers and by their 
own interest happened to be reporting more 
disappearing contacts than they had previously 
reported when they had not been interested in 
the matter. In order to check up on such possi- 
bilities, it was necessary to send an expert to 
the area. 

The first example of such a situation oc- 
curred in 1943, when a large number of dis- 
appearing contacts were reported from the 
Caribbean region by planes newly equipped 
with S-band radar (the SCR517, an Army set). 
The natural reaction of the sea frontier was to 
order the radar sets to be turned off, thereby 
preventing the U-boat from hearing the radar 
if the U-boat actually had a search receiver 
but also reducing the average search rate by 


COUNTERMEASURES 


111 


a factor of two or three. It appeared very un- 
likely to Group M that the U-boat at that time 
had S-band search receivers and Dr. Kip, then 
at Gulf sea frontier headquarters, wrote to 
Dr. Corson, the expert on Army aircraft radar 
sets, for suggestions as to other possible ex- 
planations of the phenomena. Dr. Corson sug- 
gested that “second-time-around echoes” would 
be more prevalent on the SCR517 set than on 
other S-band sets and might be the explanation. 
This effect occurs on sets with rigidly fixed 
pulse-repetition frequencies, and consists of 
echoes of the previous pulse from large, dis- 
tant targets appearing on the screen as smaller 
near targets (of range equal to the actual range 
minus the maximum range on the radar 
screen). 

Dr. Kip, and also Dr. Rinehart, then at 
Caribbean sea frontier headquarters, investi- 
gated the reports of disappearing contacts, and 
found that it was likely that “second-time- 
around echoes” were the explanation for most, 
if not all, of them. Dr. Rinehart visited several 
squadrons which had reported disappearing 
contacts, and found a pilot who claimed he 
could obtain a disappearing contact any time 
he wished by flying in a given region. Dr. Rine- 
hart accompanied this pilot on a flight and 
sure enough, a disappearing contact was ob- 
tained. A little investigation proved that the 
contact was not on a submarine which dove 
but was definitely a second-time-around echo 
from a mountain on an island some 60 miles 
away. 

A further investigation showed that this ex- 
planation would account for all of the disap- 
pearing contacts then reported. A simple change 
in the set was suggested which would serve to 
distinguish between true echoes and second- 
time-around echoes, and the brief flurry sub- 
sided. Radar sets were not turned off in anti- 
submarine planes, and the effectiveness of the 
planes in search was therefore not reduced. 

By the fall of 1943, however, the U-boats 
actually had begun using S-band search receiv- 
ers in the Bay of Biscay in small numbers. At 
this time again there arose a flurry of reports 
of disappearing contacts in American waters. 
In order to estimate the percentage of these 
reports which actually represented a U-boat 


with search receiver, Dr. B. L. Havens was 
borrowed by Group M from Radiation Labora- 
tory of Division 14 and was sent out to a 
number of bases to interview the crews which 
had reported the disappearing contacts. After 
a detailed investigation, Dr. Havens reported 
that the majority of the reports probably did 
not represent U-boats with search receivers 
and that there still was not evidence convincing 
enough to warrant turning off S-band radar in 
antisubmarine flying on this side of the At- 
lantic. 

After that time the situation changed slowly. 
The data on sightings and attacks were watched 
to see when the effectiveness of the German 
search receiver would rise to a point which 
would make a radical change in our tactics 
necessary. Even at the end of the German war 
it was not clear whether the search receiver 
had been an adequate protection to many 
U-boats. 


Tactical Countermeasures 

In the meantime, tactical countermeasures 
had to be investigated. A group member, Dr. 
M. S. Livingston, kept closely in touch with 
the development laboratories at NRL and those 
under Divisions 14 and 15 in order to know 
the details of the operational characteristics 
of radar and of search receivers so that the 
best tactics for various conditions could be 
worked out. Statements from prisoners of war 
provided some basis for estimates of the oper- 
ational properties of the German search re- 
ceiver and this enabled more definite measures 
to be suggested. 

One important question still to be settled is 
whether the only answer to an effective search 
receiver is to turn off our radar completely. A 
possibility which is still being investigated is 
some sort of intermittent operation, which pre- 
serves some of the range advantage in search 
given by the radar, but presents to the enemy 
only irregular bursts of signal which are diffi- 
cult to detect or to interpret. One technique is 
to send pulses only in flashes, bursts of a frac- 
tion of a second duration. Another possibility 
is to remove the regularity of spacing between 



112 


RESEARCH ACTIVITIES 


pulses, so that the signal heard on the search 
receiver is not a musical note, but sounds like 
a burst of static. Psychological tests, as well 
as physical ones, are being carried on to deter- 
mine the efficacy of such countermeasures. 

A property of operations research in coun- 
termeasures is the paucity of memoranda and 
formal reports which are written and the large 
percentage of personal contacts which are nec- 
essary. The data are obtained and the results are 
reported by personal interviews and confer- 
ences with the crews and officers involved. In 
this work ASWORG played a useful role as a 
technical intelligence link between operations 
and development laboratories. For effective 
liaison, it developed that this link had to be a 
personal one. 


7 7 4 Acoustic Countermeasures 

Perhaps more important than the radar 
countermeasure problem was the acoustic coun- 
termeasure problems, particularly the problem 
of countering the German acoustic homing 
torpedo. 

In the late fall of 1943, the U-boat com- 
menced using a torpedo which steered toward 
the noise of the ship. Advance information of 
such a torpedo had been obtained from prisoner 
of war statements, so that the first few cases 
of attacks using this torpedo were recognized 
for what they were. 

A number of different measures had already 
been proposed to counter acoustic torpedoes, 
and Group M was requested to make recom- 
mendations. Dr. E. A. Uehling was placed in 
charge of this part of the group’s work. 

The work in this field was voluminous and 
complicated chiefly because a countermeasure 
effective against a torpedo of one type may be 
ineffective against a torpedo with other phys- 
ical properties and may actually increase the 
danger from torpedoes of still other properties. 
The behavior of the torpedo depends very 
markedly on how it responds to intensity 
changes, how selective it is in frequency, and 
whether it can detect sounds from all direc- 
tions or only from the forward directions. A 
large number of typical “pursuit curves” were 


computed for different properties of the hom- 
ing torpedo. The various Division 6 labora- 
tories were questioned as to the possible prop- 
erties of the torpedo, and these were combined 
with prisoner of war statements to narrow the 
selection down to two or three possible types. 
An attempt was then made to find a counter- 
measure which would be good for all or nearly 
all of these types. 

In the meantime, measurements had to be 
made of ship noise and of the acoustic proper- 
ties of countermeasure gear in order that the 
physical background might be known with suffi- 
cient detail. Particularly valuable in this re- 
spect were the tests and measurements carried 
on under Commander Hummer of ASDevLant. 
The group member assigned to Commander 
Hummer, Dr. Elliot, was quite active in this 
work. On the basis of the computed curves and 
of the data from measurements, the necessary 
tactics and equipment were suggested, worked 
out, and put in use. 

As with the radar countermeasure field, the 
importance of the acoustic countermeasure in- 
vestigation, as carried on by Dr. Uehling and 
his group, was much greater than the small 
number of formal reports might indicate. Most 
of the work involved personal liaison between 
the design laboratories, the groups which were 
making sound measurements, and the officers 
responsible for doctrinal decisions. Such liaison 
is never evidenced by reports. 


78 WORK AT OPERATIONAL BASES 

Work at outlying operational bases provided 
both a schooling and a proving ground for the 
ASWORG members assigned there. Nearly all 
members on base duty were assigned desks in 
the operations room where they were able to 
witness the daily round of effort required to 
protect shipping from the U-boats. They were 
present occasionally when air crews were 
briefed or were questioned after flights and 
thus had a chance to see the multiplicity of 
small details, all of which have to be correct if 
an attack on a submarine is to be successful. 
Nothing is more salutary to an “impractical” 
scientist who has drawn up a beautifully sym- 


WORK AT OPERATIONAL BASES 


113 


metrical search plan than to see the way it 
actually turns out in practice. Nothing is more 
sobering than to see a complicated tactical plan 
rendered unworkable by the simple facts of 
seamanship or of air navigation. 

But if ASWORG members learned the “facts 
of life” at operational bases, they also turned 
out to be of some value as teachers. The oper- 
ations officers who directed the convoy escort- 
ing, the patrolling, and the U-boat hunts, were 
invariably eager to learn more in order to 
utilize their forces more effectively. Their 
basic training and the issued doctrine provided 
the framework for their operations, and issued 
directives told them the most recent changes in 
tactics. 

Most of them, however, were interested in 
learning as much as possible of the reasons 
behind the doctrines and the directives, and 
were eager to learn as completely as possible 
the capabilities of the gear which had just been 
shipped to them. Here the ASWORG member 
could be of some help. He had only recently 
come from Washington and had visited various 
development laboratories. He was acquainted, 
to some extent, with the basic theory under- 
lying the doctrine and had had a chance to go 
through some of the operational data from 
which the measures of efficiency were derived. 
He could bring to the base officers a little of 
the overall picture which might not always be 
necessary but was often helpful. 

This combined learning-teaching experience 
of the members was not limited to their con- 
tacts with the operations rooms in frontier 
headquarters. Most members on base assign- 
ment had frequently visited the lower echelons 
of command, to gain experience and to help in 
solving problems. Airfields were visited and 
operational flights were taken ; trips were taken 
on surface craft and local training units were 
visited. Mention has already been made of the 
trip on a CVE taken by Dr. Albertson. Dr. 
Kittel crossed the North Atlantic on a DE 
which was part of a convoy escort. Pellam tra- 
versed the Straits of Gibraltar in a submerged 
submarine before laying out the MAD patrol 
plans mentioned earlier. 

In many cases, the Group M member was 
asked to analyze the operational data of the 


base, in order to provide the operations officer 
with measures of efficiency for his own forces. 
These measures could then be applied as tests 
when new tactics were tried out, and as indica- 
tions of the level of experience in the different 
squadrons. In several cases such statistical 
analysis served to demonstrate to the local 
forces the advantages of following doctrine, 
such as using depth-bomb spacings of 50 ft or 
greater as compared to dropping bombs in 
salvo. In Brazil and in the Moroccan sea fron- 
tier, Group M members were able to show the 
improvement in sightings arising when patrol 
flying was directed toward estimated submarine 
positions shown on the daily COMINCH U-boat 
plot. In the Trinidad sector of the Caribbean 
sea frontier, group members were of assistance 
in preparing a monthly operations summary 
which showed to the forces operating in the 
sector what they had been accomplishing. 

A very valuable service of the member at an 
operational base was to collect specialized data 
to send to Washington for detailed study. To 
obtain many of the “measures of efficiency” 
studied by the group, complicated reports of 
an operation had to be filled out. It was often 
impractical to ask all operating forces to fill 
out such forms, and so, the members at bases 
would be asked to obtain the data for their 
region for a few months as a sample. Being 
on the spot, they could obtain the data by ques- 
tioning, without overworking the crews in fill- 
ing out forms, thus also obtaining uniformity 
of the sample. 

In many cases the group member was able 
to assist the operations officer by applying the 
theory of search in laying out barrier patrols 
or U-boat hunts. The MAD patrol in the Straits 
of Gibraltar and the barrier patrol from Brazil 
have already been mentioned. Dr. Rinehart and 
Shellard in the Caribbean sea frontier often 
assisted in laying out barrier patrols to catch 
submarines coming through one or another of 
the passages through the Antilles. Dr. Stein- 
hardt, in Brazil, assisted a number of times in 
laying out air hunt plans involving gambit 
tactics. 

Assistance was also given in getting new 
equipment effectively into use at the bases. 
Mention has been made already of the discov- 


114 


RESEARCH ACTIVITIES 


ery of the second-time-around effect with the 
Army S-band radar sets in the Caribbean. 
Shellard, at Trinidad, was of assistance in get- 
ting into operation an aircraft search receiver 
to listen for U-boat radar signals. Mr. Shellard 
accompanied the crew on a number of the trial 
flights and was able to assist in working out 
an effective search technique. The results, as 
mentioned in the previous section, were nega- 
tive but were valuable as corroboration that 
U-boats were not using radar for aircraft 
warning. 

In addition to assigning men to operational 
bases, ASWORG engaged in a few other in- 
vestigations involving trips to bases. Mention 
has been made of the investigations of Dr. 
Havens on disappearing contacts. A similar 
project on MAD contacts was undertaken by 
Dr. Judson Mead, loaned to ASWORG by the 
Airborne Instruments Laboratory, operating 
under Division 6, NDRC. 

For some time after MAD had come into 
operational use, a large proportion of seem- 
ingly false contacts on U-boats were reported. 
This tended to put MAD in disrepute in the 
operating forces. Dr. Mead was sent to the air 
fields used by some MAD-equipped squadrons 
to investigate such contacts. He soon found that 
the major difficulty was due to lack of under- 
standing of the limitations of the gear by the 
operators and the aircraft pilots. A discussion 
of these points with the squadron personnel 
served to clear up much of the difficulty and 
the experience gained by Dr. Mead enabled him 
to be of considerable aid to the Airborne In- 
struments Laboratory training program when 
he returned there. False MAD contact reports 
diminshed considerably in quantity thereafter. 

7 9 REFERENCE LIBRARY 

An essential part of every scientific labora- 
tory is its reference library. Every scientific 
work must be checked with the results of other 
investigators, various sorts of data must be 
looked up and utilized, and the results must be 
checked often with experimental measurements 
made elsewhere. ASWORG had to build up its 
reference library in order to carry on its in- 
vestigations. 


The treatment of material routed to the 
group illustrates the difference between its 
activities and those of the staff officer. The 
duties of the staff officer are primarily those 
of an executive and involve action. Reference 
to past history is seldom needed, and material 
can usually be read once and deposited perma- 
nently in the record files. The activities of 
ASWORG, however, often involved compari- 
sons, and material a year old might be as val- 
uable as last week's acquisitions. 

The necessity for constant reference to past 
history means not only that material must be 
kept, but that it must be kept in a way which 
makes it readily available. This important and 
difficult task was supervised by Dr. A. C. 
Olshen beginning November 1, 1942, when the 
Washington office files were first begun. It is 
due to his planning and care that the present 
library of approximately 7,500 technical re- 
ports is a useful tool in research. 

When the library was begun, it was realized 
that the filing system would have to be devised 
to fit the peculiar needs of the group. The sys- 
tem was worked out with great care and has 
needed only small modifications since. Each 
piece of material entering the files for perma- 
nent retention is abstracted on a card which 
is placed in the abstract file. Cross index cards 
are made to file under the various subjects 
concerned. The report is then inserted in a 
properly titled folder and placed in the proper 
section in the file drawers. Ordinarily the sub- 
ject order in the library is straightforward 
enough, so that the material can be found with- 
out need of recourse to the card index. The 
index, however, is invaluable when making a 
thorough investigation of any subject. 

7,91 Security 

A complication not ordinarily present in sci- 
entific reference libraries was the matter of 
security. Material routed to ASWORG was of 
all kinds of security classification, and the 
higher classifications had to be kept separate 
from the lower ones. This was taken into ac- 
count in the filing system and in the method 
of keeping track of the material while being 
used by group members. Since group members, 


GROUP MEETINGS 


115 


being civilians, were not under the same legal 
control as officers and enlisted men, it was felt 
important for the group to keep the strictest 
self-imposed control on matters of security. So 
important was this aspect considered that the 
equivalent of one group member’s time was 
spent in maintaining security on the reports 
used. Much of the burden of devising systems 
of security check also fell on Dr. Olshen. 

Material came to the ASWORG via two chan- 
nels, the Tenth Fleet and OSRD. All reports 
from naval sources were routed to the group 
from F-20, Combat Intelligence, via Admiral 
Low, FX-01, and Captain Fitz, FX-40. The ulti- 
mate sources were sometimes the naval labora- 
tories or bureaus, when the material concerned 
equipment. When the material concerned in- 
telligence matters, the source was often Opl6 
(Office of Naval Intelligence). Through this 
same route came reports from British sources : 
the official Admiralty reports, the Coastal Com- 
mand reviews, and the British Operations Re- 
search Section reports. 

By agreement with Admiral Low, reports 
from OSRD and the various NDRC laboratories 
were sent direct to Group M. A large library 
of NDRC reports was built up, the representa- 
tion being greatest from Division 6 (Subsur- 
face Warfare) ; but Division 14 (Radar), Divi- 
sion 15 (Countermeasures), and Division 3 
(Rockets), were also heavily represented. 


792 Routing 

The matter of internal routing was another 
subject of considerable thought and planning. 
A large number of the reports received by 
ASWORG were not for permanent retention 
but had to be returned within a short time. 
This material had to be routed rapidly and yet 
get to the proper persons. Consequently it was 
made a rule that all items, whether for eventual 
retention or not, must not be kept by a member 
for more than 24 hours. If his work required 
a longer retention, the item was returned to 
the member after the rest of the routing was 
completed. Routing sheets were kept in dupli- 
cate so as to have available a running record 
of the location of each report. 


An indication of the magnitude of this task 
and of the necessity for the great care in se- 
curity which was taken is given by the data 
on the routing of material during the month 
of August 1944. About 1,400 different reports 
were received by the group. Of these, 600 re- 
ports received very limited routing and were 
returned to the senders within 24 hours. The 
remaining 800 were given more general rout- 
ing within the group, although 460 of these 
were eventually returned to FX-40. The balance 
of approximately 340 reports, after routing, 
were abstracted, indexed, and filed in the per- 
manent files. 

If all this material had to be read by all 
members of the group, there would have been 
little other work done. It was felt expedient, 
therefore, for one experienced group member 
to spend most of his time in reading over the 
material and in routing each piece only to those 
few members whom he was sure needed it for 
their work. Consequently the average report 
was read by only 5 men instead of 30, and a 
great saving of time was obtained without a 
serious reduction in usefulness of the material. 


9 3 Distribution to Members at Bases 

In addition to maintaining a reference li- 
brary for the Washington ASWORG office, Dr. 
Olshen’s section had the responsibility of keep- 
ing up to date the small working libraries of 
the men at outlying bases. These libraries were 
necessary for their work but were, naturally, 
severely limited in size, which made the prob- 
lem of choice of material a very serious one. 
One member (usually one returned recently 
from a base) was given the responsibility of 
looking over all the material which came in to 
see what part of it might be needed badly 
enough by some one of the outlying members 
to warrant sending it to him. 


7 10 GROUP MEETINGS 

An important part of the group activities 
were the periodic meeting days where all mem- 
bers who could attend gathered together to 


116 


RESEARCH ACTIVITIES 


hear a series of formal talks in the morning 
and take part in a series of informal discus- 
sions in the afternoon. The talks were given 
by group members on various aspects of oper- 
ations research of general interest to the group 
as a whole; a report by a member recently 
returned from a base, a preliminary report of 
the results of an analytical study, a statis- 
tical report of the submarine situation, and 
so on. The agenda for these meetings were 
approved by Tenth Fleet in advance ; following 
the formation of ORG they were approved by 
the Readiness Division, 

This meeting day provided a chance for the 


members from nearby bases to bring back to 
the central group their most recent findings 
and problems, for the central group to bring 
the base men up to date on recently developed 
techniques and ideas, and also for some cross 
fertilization within the central group. 

Early in the history of the group, meetings 
were held fortnightly, and sometimes were held 
at Boston, with members of the Atlantic Fleet 
ASW Unit also attending. After 1943, the meet- 
ings were held once a month. Officers of the 
COMINCH staff, and a few other officers whose 
duties had a bearing on the work of the group 
were invited. 


PART III 


PHYSICAL RESEARCH 




Chapter 8 

FUNDAMENTAL STUDIES OF UNDERWATER SOUND 

By Carl Eckart 


81 INTRODUCTION 

A lthough the first World War stimulated 
L the development and design of devices for 
detecting and locating submarines and other 
underwater sound sources, no serious effort 
was devoted to the scientific investigation of 
underwater sound phenomena. At the end of 
World War I, the development of devices de- 
pendent for their operation upon underwater 
sound was continued by the Navy, but funda- 
mental studies of the propagation of sound in 
the sea were still neglected. General interest 
in supersonic waves did develop, but security 
barriers deflected it away from naval problems. 
Not until the early models of echo-ranging gear 
were tested did the need for more precise phys- 
ical knowledge of underwater sound transmis- 
sion become apparent. Some pioneering work 
was done by the Naval Research Laboratory 
[NRL], but the results were difficult to inter- 
pret, and therefore did not receive wide recog- 
nition. 

Why underwater sound should have been the 
long neglected stepchild of acoustical research 
is easily understood. The physical theory of 
sound propagation in both air and water had 
been developed by early investigations like 
those of Rayleigh. The study of sound propaga- 
tion in air was carried forward rapidly because 
of the continuing interest of architects, radio 
engineers, and others. It was constantly en- 
couraged by men who wanted to build better 
theaters, broadcasting studios, or radios, and 
it was given impetus and focus by the organ- 
ization of the Acoustical Society of America. 
But underwater sound seemed to have few com- 
mercial applications ; its possible importance in 
navigation has been only recently recognized. 
Naval laboratories were not in a position to 
enlist the interest of civilian physicists active 
in related fields. 

The propagation of sound in water is anal- 
ogous to that of sound in air, but few of the 
results of the last 40 years of research in air 
acoustics are directly applicable to the study 


of underwater sound. The problems are similar, 
but the answers are different. Though under- 
water sound is subject to all the seeming va- 
garies of sound in air, the quantitative aspects 
require separate determination. 

With the increased use of echo-ranging gear 
under a wide variety of oceanic conditions came 
the realization that its most effective design 
and use waited upon data that was not avail- 
able. In the hope of supplying these data NDRC 
undertook a broad program of research in 
acoustics, oceanography, and psychology. Out 
of this program came results which found a 
number of immediate applications. They pro- 
vided information which enabled the Navy to 
estimate the effectiveness of existing equip- 
ment under different operating conditions and 
to devise doctrine for its most efficient use. They 
furnished basic engineering data for the devel- 
opment of new sonar equipment. And, finally, 
they provided information which not only 
helped the Navy to modify tactical doctrine, 
but also made valuable contributions to stra- 
tegic planning. 

The NDRC program is now being continued 
under Navy auspices. There are good reasons 
for this continuation, since sound provides the 
only known method for the transfer of energy 
over any substantial distance under water. Al- 
though it is impossible to forecast the future 
accurately, it seems certain that the Navy will 
continue to depend upon underwater sound for 
assistance in many operations. 


811 Scientific Data Available in 1940 

When NDRC began its program of research 
in 1940, its scientists were able to draw upon 
three important sources of information. First, 
of course, was the great body of experimental 
data, mathematical analysis, and working 
theory which was and is the science of acous- 
tics. Second, there was a small, but very useful 
and valuable group of observations and meas- 
urements on the refraction of underwater 


119 


120 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


sound, which had been made by naval officers 
and oceanographers from the Woods Hole 
Oceanographic Institution [WHOI]. Third, 
microfilm copies of the reports prepared over a 
period of years by His Majesty’s Anti-Subma- 
rine Experimental Establishment, HMA/SEE, 
at Fairlie, Scotland, were quickly made avail- 
able. The experimental results of NRL, men- 
tioned above, were also available. 

Research carried on for the Army or Navy 
is like all other research in that it builds on 
the foundation of pre-existing fundamental sci- 
entific knowledge. So it was with the investiga- 
tions of underwater sound. Though the NDRC 
scientists found that former investigations of 
airborne sound had solved disappointingly few 
of their problems, they naturally began with 
all the existing theoretical and mathematical 
analyses of sound transmission that seemed 
applicable to their work. 

The body of special oceanographic informa- 
tion available to them, together with the obser- 
vations of sound gear performance which had 
been made by American and British naval per- 
sonnel, indicated the directions in which their 
research might go. Thus they knew that sound, 
unlike light and radio waves, should theoret- 
ically travel great distances underwater with- 
out great loss of energy. But published experi- 
mental results on fresh water and other liquids 
showed that the attenuation of sound, though 
not so great as to make the use of sound gear 
impractical, was frequently far greater than 
that predicted by theory. The NRL results 
confirmed this for sea water and in addition 
showed that the attenuation was extremely vari- 
able from day to day, or even from minute to 
minute. The primary reason for the anomalous 
behavior of sound in the ocean was recognized 
by the Woods Hole oceanographers as the re- 
fraction of sound by temperature gradients. 
Finally the HMA/SEE reports contained val- 
uable material on reverberation, theoretical 
discussions of the acoustic properties of bub- 
bles and of target strength, and data on the 
variability of echo intensity. 

8,1,2 The Research Needed 

The sonar gear carried by submarines and 


surface vessels is required to do many things. 
It is used to detect the presence of ships, sub- 
marines, swimmers, and mines at the longest 
possible ranges. Ideally, it should locate them 
accurately, giving their bearing, range, and 
(for mines and submarines) depth. When used 
to locate moving targets, sonar gear should 
show their speed and course, and, when possi- 
ble, give some indication of the kind of engines 
and screws that drive them. 

At the time of writing this report no gear is 
available which does all these things. Sonic 
submarine listening gear, for instance, may de- 
tect a surface vessel at ranges greater than 
5 miles. At this distance, however, it can give 
only approximate bearings and no estimate of 
range. As the range closes, an experienced 
operator may be able to identify the engines 
and screws that create the signal to which he 
listens ; he can also get more accurate bearings. 
But present listening gear cannot give him re- 
liable reports of range. 

Echo-ranging gear, similarly, has marked 
limitations. It cannot be relied upon to detect 
a submarine at ranges greater than 3,000 yd, 
and maximum echo ranges on mines have usu- 
ally been less than 500 yd. Though echo-ranging 
gear may give the operator clues to target 
speed and course, it can tell him nothing about 
the design or construction of a target. Only 
recently has echo-ranging gear been devised to 
show the depth of a target and the problem of 
maintaining contact on a deep target at close 
range is still being studied. 

Nor is this all. Maximum echo and listening 
ranges are extremely variable. They may be 
affected by the speed of the searching ship, by 
the speed, size, and aspect of its target, by sea 
state, by temperature gradients, by the pres- 
ence or absence of various forms of marine life, 
and by the depth of the water. In shallow water, 
they are affected by the ocean bottom. They 
are also affected by the skill and ability of the 
operator, since the detection of a target with 
any sound gear depends upon recognition of a 
signal in the presence of background sounds 
tending to mask it. 

Thus maximum listening ranges depend upon 
four things, most of which are affected by 
oceanographic conditions : 


NDRC PROCEDURES 


121 


1. The characteristics of the sound emitted 
by the target. 

2. How much and in what way the signal is 
weakened by traveling to the listening hydro- 
phone. 

3. The nature and strength of the noise tend- 
ing to mask the signal. 

4. The ability of the eye or ear to distinguish 
the signal from the background noise. 

The variables determining maximum echo 
ranges are similar and more numerous : 

1. The characteristics of the transducer 
(sound source). 

2. How much the signal is weakened by 
traveling to the target. 

3. How much sound the target returns to the 
echo-ranging vessel (target strength). 

4. How much the echo is weakened in re- 
turning from target to hydrophone. 

5. The character and strength of the back- 
ground noise. 

6. The character and strength of the rever- 
beration. 

7. The ability of eye or ear to distinguish 
between echo and background. 

Studies of sound transmission are conducted 
by physicists and recognition is studied by 
psychologists. But the medium through which 
sound moves is the sea, and most of the noises 
tending to mask or obscure a signal originate 
in the sea or are modified by transmission 
through it. Consequently the physicist and psy- 
chologist must work not only with electrical 
and acoustical engineers and representatives 
of the Navy, but with oceanographers, geolo- 
gists, and marine biologists. Out of their coop- 
erative study has come our present knowledge 
of the behavior of sound in the sea. 

At the beginning of World War II, it would 
have been practically impossible to have writ- 
ten the paragraphs above. The cooperation of 
the many specialists listed was necessary in 
order to formulate the problems to be solved. 
Civilians, and in some cases even naval author- 
ities, were unaware of the operational problems 
that sonar gear would be called upon to solve. 
For example, the development of gear adapted 
to the location of midget submarines, swim- 
mers, and mines had not even been considered 
in 1941. 


8 2 NDRC PROCEDURES 

Woods Hole Contract 

When NDRC first undertook to provide for 
basic research on the transmission of under- 
water sound, it turned to the Woods Hole 
Oceanographic Institution. Through continued 
contacts with the Navy in the years before 
World War II, the piembers of the Woods Hole 
staff had acquired a realistic knowledge of 
Navy problems. In this, they were unique 
among civilian scientific organizations. They 
had also made a good start in the study that 
NDRC was taking up, for they had collected a 
substantial quantity of data, not only on under- 
water sound transmission, but also on oceano- 
graphic problems which might prove relevant. 
They had developed the bathythermograph 
[BT] for the rapid measurement of the tem- 
perature of the ocean at various depths, and 
which could be used from a moving ship. They 
had shown that this subsurface weather was 
important in determining sound transmission. 
They had developed a theory (refraction 
theory) of this effect, which was necessarily 
oversimplified, but which has continued to play 
an important part in the interpretation of later 
information. In 1940, therefore, NDRC entered 
into a contract with WHOI. 

San Diego Contract i 

When, in the spring of 1941, NDRC was 
asked by the Navy for further assistance in 
the development of underwater sound devices, 
those responsible for the NDRC program rec- 
ognized the need for a more intensive investi- 
gation of underwater sound phenomena than 
the Woods Hole staff could prosecute alone. 
They also recognized that such work could best 
be done at some location which was near deep 
water and adjacent to large Navy organizations 
and units. The shallow continental shelf of the 
Atlantic coast made deep water relatively in- 
accessible, so the investigators, in selecting a 
laboratory site, naturally turned to the Pacific 
coast. San Diego provided a unique location, 
since the 600-fathom San Diego Trough is 
located only 15 miles offshore. Later, the need 
for experiments in shallow water caused a 
transfer of some activities back to Woods Hole. 


122 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


NDRC therefore entered into a contract with 
the University of California, making provision 
for the establishment of a new research group 
at San Diego. Housed at the U. S. Navy Radio 
and Sound Laboratory (now the U. S. 
Navy Electronics Laboratory), the Univer- 
sity of California Division of War Research 
[UCDWR] began to supplement the research 
already under way at Woods Hole. The staff of 
scientists engaged in this work was assisted by 
contacts with the staff of the Scripps Institu- 
tion of Oceanography [SIO], located at La 
Jolla, some 12 miles away. This institution had 
accumulated data on oceanographic conditions 
in the Pacific, and particularly on the condi- 
tions off the Southern California coast, and 
some of its staff transferred to UCDWR. 

Sonar Analysis Group 

As experimental data began to be accumu- 
lated by UCDWR and the WHOI, it became 
desirable to assign a small group of physicists 
and mathematicians to its analysis. These men 
were employed under the Columbia University 
contract and later became known as the Sonar 
Analysis Group. Taking experimental data 
from the two NDRC research organizations 
and Navy laboratories, as well as from special 
studies carried on under other contracts, the 
Sonar Analysis Group conducted analyses to 
determine the bearing of research findings 
upon problems of design and operation. Work- 
ing in very close liaison with interested sections 
of the Navy, this group was able to interpret 
and aid in the immediate utilization of the in- 
formation which was being gradually accumu- 
lated. 

The slowness of this accumulation was in- 
evitable. Even in peacetime, it would have been 
slow, for analysis and interpretation of results 
cannot be carried on hastily even by the best 
qualified men. There were very few men who 
had previously given thought to these problems, 
and they were usually assigned to the develop- 
ment of urgently needed gear. The great num- 
ber of competing scientific programs during 
World War II limited the staff of the under- 
water sound groups, thus reducing the number 
of problems that could be considered. The quali- 
fications of some of the men engaged in the 


work were not specifically suitetl to the re- 
search at hand, but they made up for lack of 
formal training by enthusiasm for the work, 
and accomplished more than could have been 
anticipated. 

New problems were constantly being uncov- 
ered by the operations of the Navy, or raised 
by the new tactics and weapons of the enemy. 
Through the mediation of the Sonar Analysis 
Group, these problems were communicated at 
once to those actively engaged in the scientific 
work. All too often, the urgency of the new 
problems caused the interruption of important 
but less urgent work. Although the hasty ex- 
periments and conclusions (again communi- 
cated to the Navy via the Sonar Analysis 
Group) were valuable, those actually engaged 
on the work constantly suffered from the fear 
that their efforts would be “too little and too 
late.” 

Navy Observational Program 

The Navy also initiated an extensive obser- 
vational program, installing bathythermo- 
graphs on an ever increasing number of combat 
vessels. A farsighted policy initiated this pro- 
gram even before the data obtained could be 
effectively used in operational planning. The 
results of the observations in the Atlantic were 
transmitted to WHOI, and of those in the Pa- 
cific, to UCDWR. There, NDRC groups sub- 
jected them to analysis and tabulation and 
worked out methods for the immediate use of 
new data for operational purposes. The close 
cooperation between the Forces Afloat, the 
Bureau of Ships, and the civilian scientists, 
made this one of the most successful NDRC 
programs. Its only handicap was lack of time. 
Had it been initiated some years earlier, even 
on a small scale, it would have been even more 
effective. 


8 3 SCIENTIFIC DATA SECURED BY 
NDRC AND THE NAVY 

Two methods of approach are possible in a 
report of extensive scientific studies of closely 
related phenomena. One is the textbook treat- 
ment, the systematic exposition of theory and 


SCIENTIFIC DATA SECURED BY NDRC AND THE NAVY 


123 


supporting data. The other is historical, giving 
the organization and experimental methods of 
the scientists, and recording their mistaken as- 
sumptions and false starts as well as their 
progress. The method of this chapter is a kind 
of hybrid, in so far as it is both and neither; 
it merely outlines the complexity of the re- 
search, the way in which it has been carried 
on, and some of its most important findings. 
The history of each NDRC contract is given 
fully in its completion report, and most of the 
results of the underwater sound research pro- 
gram have been reported both systematically 
and fully in other volumes of this series, as well 
as in special publications of the Sonar Analysis 
Group and the Bureau of Ships. 


Transmission Studies 

The chief problem of transmission studies 
is the measurement of the sound field of any 
source as a function of oceanographic condi- 
tions. When the sound is complex, such meas- 
urement requires a number of analyses of in- 
tensity and spectrum as functions of range and 
hydrophone depth. When the source, such as a 
submarine, can vary in depth, that variation 
must also be measured. Time variations further 
complicate transmission studies, since a single 
pulse may sometimes travel by different paths 
to arrive at a hydrophone as a series of dis- 
crete or interfering pulses. Even when the 
source emits a steady tone of constant inten- 
sity, a hydrophone more than a few yards away 
receives a sound of fluctuating intensity. 

Measuring the effect of oceanographic condi- 
tions on sound transmission differs from most 
laboratory problems in that complete control 
of experiments is impossible and the separation 
of independent variables is exceedingly diffi- 
cult. Experiments must be carefully planned, 
but the subsurface “weather” cannot be 
planned. Consequently large quantities of data 
must be accumulated in the hope that eventu- 
ally all combinations of variables will occur. It 
is impossible to bring the sea to the laboratory, 
so the laboratory must put to sea, collect all the 
data which may be possibly relevant, and bring 
it back for analysis. Studies are made in water 


of varying depth, over bottoms of different 
character, in dead calms and near gales, at 
various frequencies, at different times of day 
and night, and in different seasons. So many 
variables affect every observation that it re- 
quired months of experiment to establish the 
effect of any one variable (ipon sound trans- 
mission. 

Transmission studies have been made with 
many different sound sources. Thus studies 
have been made of the transmission of ship and 
screw sounds, of the output of various types of 
noisemakers used in mine sweeping, of explo- 
sions, and of the sound emitted by standard 
echo-ranging projectors, as well as by specially 
constructed transducers emitting one or more 
frequencies. During the progress of the work, 
greater and greater use has been made of spe- 
cial transducers. 

Sound Sources 

The behavior of sound in the sea depends 
considerably on its source. Thus the transmis- 
sion of the sound beam of a sonar projector is 
different from that of the sound of submarine 
screws and machinery. The determination of 
the characteristics of sound sources was there- 
fore an important part of the NDRC program. 

The characteristics of sonar projectors and 
receivers were studied at calibration stations 
constructed on piers and barges. Some of these 
were located in harbors, as at New London and 
Point Loma. The work at these locations was 
hampered in two ways by traffic in neighboring 
waters. Passing ships produced so much noise 
that special precautions had to be taken to pre- 
vent interference with the measurements. 
Nearby ship-building operations and pile- 
drivers were other offenders. A second diffi- 
culty was experienced when small craft passed 
near the apparatus. The bubbly water of the 
wake would drift into the region traversed by 
the experimental sound and make measure- 
ments impossible for a period of minutes. 

To obtain more accurate data, calibration 
stations (see Section 9.3.3) were established in 
small fresh-water lakes: at Mountain Lake, 
New Jersey; Orlando, Florida; and at Sweet- 
water Dam near San Diego. Even these loca- 
tions were not entirely satisfactory, since the 


124 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


water was very shallow; Sweetwater station 
was relatively good, since the artificial lake had 
been constructed in a deep narrow canyon. 

It was found that these stations were indis- 
pensable to any development work involving 
either projectors or hydrophones. Regularly 
scheduled station wagons and trucks operated 
between the Sweetwater station and the Point 
Loma laboratory, and made close cooperation 
possible. 

The characteristics of ships and submarines 
as sound sources can be measured only in the 
open sea. This brought other problems with it. 
The calibration equipment had to be mounted 
on shipboard. The noise of the laboratory vessel 
interfered with the operation, so that some 
attempt was made to work from small row- 
boats. This was unsatisfactory because of the 
limited space and electrical power. No one so- 
lution was found, but a useful expedient was 
to suspend the hydrophone from buoys floated 
out from the laboratory vessel, and cable-con- 
nected to the equipment aboard ship. 

Hundreds of measurements were made of the 
sound output of all types of vessels, ranging 
from submarines to battleships and aircraft 
carriers. One accidental observation which 
showed that some carriers had “singing” pro- 
pellers led to efforts by NDRC and USNRSL 
to initiate a systematic survey. A relatively 
minor change in propeller design is said to have 
eliminated this very undesirable type of sound. 
But even at the end of the war, some carriers 
were dangerously noisy. Greater care was given 
by the Navy to the quieting of submarines and 
NDRC personnel often cooperated in obtaining 
necessary data. 

These measurements of ship sounds have 
been collected and summarized in a report. Al- 
though some general conclusions of permanent 
value have been reached, it should be noted that 
these data are essentially ephemeral. The sound 
output of a ship is affected by maintenance and 
by the installation of new auxiliaries. Slight 
injuries to the propeller, such as can be caused 
by a bit of driftwood, may raise its sound out- 
put many decibels. Consequently an active pro- 
gram of measurements must be maintained at 
all times and coordinated with a program of 
corrective measures. 


An entirely different set of sound sources — 
those found in nature — was also studied by 
NDRC. These background noises interfere with 
the detection of echoes and other wanted 
sounds. They have many causes, ranging from 
marine life (for example, porpoises, snapping 
shrimp, and croakers) to breaking waves. The 
levels of background noise, as a function of 
meteorological and oceanographic conditions 
were studied. It was found, for example, that 
certain kinds of biological noise could be pre- 
dicted with considerable accuracy. 

Certain noises heard in sonar gear, originat- 
ing in the ship which carries it, could not be 
effectively studied during the war because of 
the unavailability of combat ships for sufficient 
periods of time. Some beginning has been made 
on this problem since the end of World War 
II, but corrective measures have not yet been 
considered. 

Attenuation Coefficient 

Sound traveling outwards from a source al- 
ways weakens with distance. Even if it travels 
through a perfect medium, so that none of its 
energy is scattered or dissipated into heat, the 
wave front spreads regularly over larger and 
larger areas. Thus the total energy in the sound 
wave is spread ever thinner, and the intensity, 
which is the concentration of energy in any 
region, decreases regularly with the distance 
from the source. If the source is assumed to be 
a point, the intensity of the sound which it ra- 
diates should decrease inversely as the square 
of the range. 

Actually, of course, a point source has no real 
existence, so that the intensity loss caused by 
spreading of sound from any source will be 
somewhat different from that predicted by the 
inverse square law. If, however, the intensity 
of the sound from any source is measured at a 
hundred yards and the strength of the source 
is then expressed in terms of a point source 
which would be required to produce the same 
intensity, the inverse square law can usually 
be used to calculate the losses due to regular 
spreading. 

It cannot be used to calculate all effects, since 
(1) the ocean is a bounded medium, and sound 
is reflected by its surface and bottom; (2) 


SCIENTIFIC DATA SECURED BY NDRC AND THE NAVY 


125 


changes in the pressure, temperature, and 
salinity of the ocean may result in changes in 
the velocity of sound and so change both the 
sound path and the way sound spreads; and 
(3) the ocean is a somewhat less than perfect 
medium, so that some energy is lost by absorp- 
tion and scattering. These facts combine to re- 
sult in observed transmission losses which can 
depart widely from values predicted by the in- 
verse square law. This discrepancy between the 
calculated inverse square loss and the meas- 
ured loss is sometimes called the transmission 
anomaly. 

The transmission anomaly cannot be exactly 
predicted from oceanographic observations, 
since even when conditions are seemingly con- 
stant, observed transmission losses are highly 
variable. At the present time, therefore, only 
average figures can be given for the value of 
the anomaly under various conditions. 

Transmission is best when the water through 
which sound moves is so well mixed that com- 
monly used measuring devices show no varia- 
tion of temperature with depth. In the absence 
of measurable temperature gradients, the 
water is said to be isothermal, and very little 
of the transmission anomaly can be attributed 
to changes in the velocity of sound. When meas- 
urements are made with highly directional 
supersonic transducers in deep water, bottom 
reflection can also be ignored. Under such con- 
ditions, the anomaly is found to be roughly 
proportional to the range. 

This increase of the anomaly with range is 
called attenuation, and the amount of that in- 
crease, measured in decibels per kiloyard, is 
called the attenuation coefficient. In water 
which is isothermal from the surface to a depth 
of 200 ft or more, the attenuation coefficient is 
relatively constant at any one frequency, and is 
found to increase with increasing frequency. 
Thus it is about 3 db per 1,000 yd at 16 kc, 4 
db per 1,000 yd at 24 kc, and 15 db at 1,000 yd 
at 60 kc. At very low frequencies, on the other 
hand, it seems to be negligible, so that sonic 
sounds trapped in a “sound channel” may 
travel for thousands of miles and still be heard. 

It has been found that the attenuation of 
sound in the sea is 40 to 300 times greater than 
it should be on the basis of simple theory. On 


the other hand, it is 100 to 200 times less than 
would be expected from laboratory measure- 
ments at high frequencies in fresh water. This 
is one of the outstanding scientific problems of 
underwater sound. 

Determination of an attenuation coefficient 
becomes much more difficult when temperature 
gradients are present in the top 100 ft of the 
ocean. When, for instance, there are small 
gradients within 50 ft of the surface, the aver- 
age attenuation in the shallow isothermal layer 
is generally about twice as great as it is when 
the isothermal layer is deeper, but it is also 
much more variable. Finally, when there is a 
strong negative temperature gradient begin- 
ning at the surface, transmission anomaly does 
not show a simple proportionate increase with 
range. Temperature gradients cause the sound 
rays to curve, so that the spreading of the 
sound obeys more complicated laws and ob- 
scures the effects of attenuation. 

Refraction Theory 

Early tests of echo-ranging gear showed that 
maximum ranges were sometimes dramatically 
reduced in the afternoons of calm clear days. 
During the morning a target might return 
echoes at ranges of more than 3,000 yd ; in the 
afternoon, it might not return echoes even at a 
range of only 500 yd. Careful observations of 
this afternoon effect enabled Woods Hole scien- 
tists to establish the fact that it was produced 
by shallow negative temperature gradients in 
the upper 30 to 50 ft of the ocean. 

The explanation was simple. Since the water 
near the surface was warmer than any below 
it, that part of a wave front which was nearest 
the surface traveled faster than the part which 
was deeper and in colder water. Therefore the 
whole wave front curved toward the region of 
lowest temperature, much as a ship turns in the 
direction of its slowest propeller. The sound 
beam was “bent” and headed for the bottom. 

To put it in another way, all sound rays leav- 
ing the projector were bent downward. The 
one which left the projector at an angle high 
enough above the axis to become horizontal at 
the surface was the one which traveled far- 
thest. It was the “limiting ray.” Rays leaving 
at higher angles were reflected or lost at the 


126 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


surface. Rays leaving at smaller angles never 
reached the surface, since they were bent to- 
ward the bottom before reaching the top. Be- 
yond the limiting ray was the “shadow zone,” 
a region into which no sound could penetrate. 

This explanation of afternoon effect led nat- 
urally to an extensive theoretical development 
of refraction theory. As already mentioned, the 
Woods Hole scientists had developed the bathy- 


negative gradient beginning at the surface ; the 
other shows the predicted path of a beam pro- 
jected into isothermal water lying above a layer 
of sharply decreasing temperature. Because the 
depth scale is much larger than the range scale, 
ray bending is exaggerated. 

During the early months of research at both 
WHOI and UCDWR, slide rules and tables for 
the calculation of ray paths were prepared, and 


TEMPERATURE 


4000 



Figure 1 . Sound ray diagrams: (A) predicted effect of negative gradient beginning at the surface; (B) 
predicted effect with isothermal layer above negative gradient. 


thermograph, with which a continuous record 
of temperature as a function of depth could be 
obtained. Using such a record, they could cal- 
culate the velocity gradient (the change in the 
velocity of sound with depth) and then calcu- 
late the path of any sound ray leaving an echo- 
ranging projector. Given enough ray paths, 
they could make a “ray diagram.” 

Two ray diagrams are shown in Figure 1. 
One shows the predicted result of a marked 


collections of archetypal ray diagrams grew. 
Two assumptions were implicit in much of this 
activity. It was assumed that the predicted 
shadow zone always had a real existence: that 
transmission was determined completely by the 
ray diagram, and that the ray diagram could 
be used to predict sound intensity in all parts of 
the sound field. Thus, the predictions were: no 
sound in the shadow zones, weakened sound 
where rays were widely spread, and little or no 


SCIENTIFIC DATA SECURED BY NDRC AND THE NAVY 


127 


anomaly where normal spreading was not ac- 
centuated by bending of the rays. 

Although these assumptions were useful, and 
were supported by some evidence, they were 
not the whole truth. Transmission studies be- 
gun at San Diego in 1943 proved that shadow 
zones do not always occur when refraction 
theory predicts them, and that when they do 
occur they are not utterly soundless. Intensi- 
ties within the predicted sound field, similarly, 
are affected by many things, though refraction 
may be extremely important. 

One product of refraction is the commonly 
observed layer effect, the partial protection 
from detection by listening or echo ranging 
which a submarine gains by submerging below 
a layer of sharp negative gradient. Whenever 
a beam travels from an isothermal layer into a 
negative gradient, the sound rays are so turned 
and spread that there is a marked drop in the 
intensity of the sound. Consequently the echo 
range on a submarine below a layer may be 
less than half the range on one above. 

Refraction theory is best borne out by the 
condition which led to its formulation. A pre- 
dicted shadow zone materializes only when 
there is a strong negative gradient starting at 
the surface. Then the sound within the shadow 
zone is more than a thousand times weaker 
than that in the direct sound field. There is 
some sound in the shadow zone, it is true, but 
not enough to produce an audible echo from a 
submarine. What little sound there is probably 
results from the forward scattering of sound, 
or perhaps by a deep scattering layer, called 
the ECR layer. It is discussed in more detail in 
following text. 

Under no other conditions do shadow zones 
exist. With all other types of temperature dis- 
tributions, no matter what the ray diagram 
predicts, sound intensity at any given depth 
diminishes regularly with range. There is no 
point beyond which the intensity drops sharply. 

Surface and Bottom Reflection 

When sound energy reaches the ocean’s sur- 
face or bottom, any of three things can happen 
to it. It can be reflected back as from a mirror, 
with a sharply changed direction but little loss 
of intensity; it can be scattered back into the 


medium in all directions ; or it can be lost by 
transmission through the boundary into the air 
or earth. Ordinarily some of the sound is re- 
flected, some scattered, and the rest lost, in 
amounts depending on conditions at the bound- 
ary. 

Ordinarily, about half the sound from any 
source reaches the surface (unless, of course, 
a directional source is pointed toward either the 
surface or bottom: i.e., a fathometer pointed 
downward, or a Herald tilted toward the sur- 
face) . Very little of the sound reaching the sur- 
face escapes to the air; more than 99 per cent 
of it is either reflected or scattered back. If the 
surface is smooth, almost all the sound is re- 
flected. But if the surface is much disturbed by 
waves, winds, or currents, a large proportion of 
the incident sound may be scattered. 

In echo ranging, the scattering of sound by 
a disturbed surface results both in high noise 
and in high reverberation levels, as well as in 
an increase of attenuation. The reflection of 
sound by a smooth surface, on the other hand, 
never shortens echo ranges; sometimes it re- 
sults in marked extension of ranges when shal- 
low positive temperature gradients warp the 
sound beam toward the surface. 

In listening, high sea states frequently re- 
duce ranges by increasing both the attenuation 
and the loudness of the background noise over 
which the signal must be heard. With low sea 
states, ranges are ordinarily longer, though 
sometimes the intensity of audible sounds may 
be reduced by interference between direct and 
surface-reflected sound. This interference tends 
to cut down the intensity of audible sound at 
intermediate ranges and to cause irregular 
changes in intensity at short ranges. 

At long ranges, almost all of the sound re- 
ceived from a shallow nondirectional source has 
been reflected from the bottom. The importance 
of reflection and scattering by the bottom de- 
pends both on the nature of the sound source 
and on the depth of the water. Thus a noisy 
ship, which is a powerful sound source emit- 
ting sounds of many frequencies in all direc- 
tions, may be heard at great distances even in 
deep water. This is true under all thermal con- 
ditions. At these ranges, the higher frequencies 
have been so weakened by attenuation that only 


128 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


the low-frequency components are heard. In 
echo ranging, on the other hand, the sound 
source is a highly directional supersonic pro- 
jector which beams most of its output hori- 
zontally. Consequently, little sound reaches a 
deep bottom, and the little that does is so weak- 
ened by attenuation that its reflection has no 
effect upon maximum echo ranges in deep 
water. 

In shallow water, however, bottom effects are 
important. Experiment has shown that the 
amount of sound scattered or reflected by the 
bottom depends roughly upon the “hardness” 
and “smoothness” of the bottom. Thus soft mud 
absorbs much of the sound striking it ; although 
it may scatter enough sound from an echo- 
ranging ping to raise reverberation levels, it 
reflects very little sound. Sonar ranges over 
mud, therefore, are much like those in deep 
water. 

Harder bottoms reflect more sound, so that 
listening ranges over sand, rock, and stony bot- 
toms are frequently lengthened by bottom re- 
flection. Echo ranges over sand may be simi- 
larly extended, but over rock another effect 
more than compensates for the reflection, for 
the ranges are usually shortened by the roar 
of reverberation caused by the scattering of 
sound by the rough, irregular bottom. 

Accurate prediction of sonar ranges and 
transmission losses in shallow water waits 
upon more extensive studies and careful classi- 
fications of bottom character. Enough was dis- 
covered during the war to show that such re- 
search can be extremely valuable ; submariners, 
for instance, are particularly interested in find- 
ing the ocean areas with the best “natural 
cover.” Operating in such areas, they are least 
likely to be detected with sonar gear. 

Fluctuation 

Many months of experiment and analysis 
have been required to establish the effect of tem- 
perature gradients, sea state, and bottom type 
upon sound transmission. Today, however, the 
findings of the NDRC program have enabled us 
to explain and even to predict the average 
transmission loss under known conditions. The 
explanations are not complete, and the predic- 
tions are less accurate than they should be, but 


average transmission losses seem explicable 
and calculable. 

The joker is hidden in the word “average.” 
With standard echo-ranging gear, for instance, 
which has a nearly constant output, and with 
carefully measured oceanographic conditions 
(bottom character, temperature gradients, sea 
surface) , only the average intensity of a series 
of pings received by a distant hydrophone is 
calculable. Though all conditions may seem to 
be constant, the intensity of one ping may differ 
from that of the next by as much as 20 db. The 
intensity of most pings, it is true, will lie some- 
what closer to a median value, but about one in 
ten will be more than 10 db below the median. 

A similar fluctuation may be observed in the 
character or “envelope” of successive pings. 
Thus the short “square” pulse of sustained in- 
tensity put into the water by an echo-ranging 
projector may be received by a distant hydro- 
phone as a signal of fluctuating intensity, or 
as a short crescendo or diminuendo. When this 
distortion is considered together with the ping- 
to-ping fluctuation of intensity, the problem of 
predicting the range at which a submarine can 
be certain of getting an audible echo from a 
single ping becomes extremely knotty. 

The causes of fluctuation can be guessed at 
but they have not yet been established by ex- 
periment. It may be, for instance, that the sig- 
nal travels by several paths; when sounds 
which have traveled different ways reach the 
hydrophone, the intensity of the signal depends 
upon their phase relationship. If they are in 
phase, they reinforce each other to produce a 
strong signal. If they are out of phase, they in- 
terfere with each other to produce a weak 
signal. 

Another cause of ping-to-ping fluctuation 
may be small variations in the vertical and 
horizontal temperature structure of the ocean. 
Although a single bathythermograph record 
shows the gross vertical temperature structure 
of the ocean at the point where it was made, 
records taken at various points along the trans- 
mission path may show variations in that struc- 
ture. Then, too, the structure in any one place 
may change from ping to ping ; internal waves, 
for instance, may regularly raise and lower the 
thermocline. Finally, the temperature micro- 


SCIENTIFIC DATA SECURED BY NDRC AND THE NAVY 


129 


structure of the ocean is almost completely un- 
known ; small, local changes in temperature are 
omnipresent, and their effect is unknown. 

Fluctuation, in other words, stands near the 
top of the list of problems marked for further 
study. 

Echo Formation and Target Strength 

Echo ranges depend not only upon the initial 
sound level and the transmission loss, but also 
upon what might be called the “acoustic size” 
of the target. This is merely another way of 
saying that the more sound a target intercepts 
and returns to an echo-ranging vessel, the 
louder will be its echo. 

Generally speaking, a large target returns a 
louder echo than a smaller target at the same 
range and depth, and the echo from any par- 
ticular target is louder at beam aspect than at 
bow or stern aspect. To compare various tar- 
gets and aspects, the “target strength” is a 
useful number ; it is measured in decibels. 

The target strength of a ship or submarine 
depends on both its size and its aspect, but pre- 
sumably not on its range nor on oceanographic 
conditions. Thus the target strength of any ship 
at given aspect is a constant. The experimental 
measurement of target strength, however, is 
not an easy matter. There are many sources of 
error, and since the measurements must be 
made in deep water, it is difficult to control 
them. Difficult problems of seamanship also 
arise in these operations. 

Theoretically, target strength is not a simple 
function of target size. The processes of echo 
formation are complicated, and target strength 
depends not only upon the amount of sound in- 
tercepted, but also upon the nature and shape 
of the reflecting or scattering surfaces. A 6-ft 
triplane, for instance, which is a structure so 
designed that most of the sound incident upon 
it is reflected back toward its source, theo- 
retically has the target strength (for 24-kc 
sound) of a sphere about 100 ft in diameter. 
Practically, it has a target strength somewhat, 
but not much, less than a submarine. 

Wake Studies 


they returned echoes several hours after they 
had been laid. Interest in submarine wakes 
arose from reports that submarines could some- 
times confuse echo-ranging pursuit by creat- 
ing “knuckles” during evasive maneuvers. The 
study of wakes became imperative when nec- 
essary to design countermeasures against 
acoustic torpedoes, and their effect on our own 
acoustic torpedoes then became a matter of con- 
cern. 

Few of the phenomena involved in under- 
water sound transmission studies are so diffi- 
cult to study. Among other things, many ex- 
periments involve some danger, even when 
conducted with excellent seamanship. Once, for 
instance, when the UCDWR laboratory was 
working with destroyer wakes, a new commo- 
dore came on the bridge of his flagship just in 
time to see that it was bearing down rapidly on 
a yacht lying dead in the water while a small 
boat was apparently intending to ram the de- 
stroyer. It was with difficulty that he was dis- 
suaded from giving a number of anxious 
orders. As it turned out, his fears were almost 
justified, for the force exerted by the moving 
vessel on the nearby stationary vessel (Ber- 
noulli effect) was great enough to draw the 
yacht into the destroyer's wake less than 100 
ft behind the destroyer’s stern. 

Skillful seamanship and careful coordination 
prevented any serious accidents, even when 
submarines operated very near surface vessels. 
But the work was frequently unrewarded by 
results, since the failure of a single part of the 
program could vitiate all others. 

Consequently it is felt that the problem 
should be approached indirectly, through lab- 
oratory work and theoretical calculations, and 
through studies of related problems like turbu- 
lence. 

During the war, the rapidly planned and exe- 
cuted empirical studies produced useful infor- 
mation on transmission loss through wakes, re- 
flection from wakes, and the intensity of pro- 
peller sounds in wakes, but much remains to be 
done. 


Interest in the acoustical properties of sur- 8 3 2 Noise Studies 

face wakes was first stimulated by reports that Whatever the signal level, detection of the 


130 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


signal depends upon its relationship to the un- 
wanted sounds which are being received at the 
same time. A signal which is easily detected at 
one time may be masked by high background 
noise at another. This is, of course, what com- 
mon experience might lead anyone to suspect; 
a sneeze, for instance, is clearly audible in a 
library reading room, but goes unremarked in 
a boiler factory. In much the same way, a loud 
echo may be unmistakable when an echo-rang- 
ing ship is making less than 15 knots in deep, 
quiet water; the same echo might never be 
heard if the ship were speeding through a 
rough, shallow sea, with its pings reverberat- 
ing from a rocky bottom and mixing with the 
sound produced by large and noisy settlements 
of snapping shrimp. Therefore the study of 
echo ranging and listening necessarily involves 
the measurement and analysis of background 
sounds, as well as of the ability of operators to 
distinguish between signals and masking 
sounds. 

Types of Noise 

If a ship is alone in the open sea, drifting 
with wind and current, and with engines 
stopped, noise can still be heard in a hydro- 
phone. This is called the ambient noise, since it 
surrounds, but is independent of, the listening 
vessel. If the ship starts its engines and begins 
to move through the water, the loudness of the 
noise increases. To the sea sounds is added the 
self noise produced by the engines and pro- 
pellers, and by the movement of hull and hydro- 
phone through the water. 

All these noises pass through the same re- 
ceiver that amplifies the signal. They may, con- 
sequently, be called the amplified noise, and are 
so distinguished from the airborne noise such 
as orders, explosions, bells, and aircraft sounds, 
which can distract an operator even though 
they are not amplified by his equipment. Un- 
amplified airborne sounds should not ordinarily 
limit sonar ranges, since the sonar ought to be 
located in a reasonably quiet part of the ship 
and in a sound-conditioned room. During World 
War II, however, such a location was not al- 
ways possible. The masking of signals by the 
sounds which are not airborne is a more diffi- 
cut problem, since any amplification of the sig- 


nal also amplifies the noise ; no matter how high 
the gain, the relationship between signal and 
amplified noise remains constant. 

Self-noise levels vary from ship to ship, 
since they are affected by the design and main- 
tenance of the engines, hull, and propellers, as 
well as by the housing and location of the hy- 
drophone. Certain generalizations, however, 
can be made on the basis of data taken by the 
Navy and NDRC scientists. Sonic self-noise in- 
creases so rapidly with increasing ship speed 
that Allied antisubmarine vessels during World 
War II seldom attempted to detect or track sub- 
marines with sonic listening gear. Echo-rang- 
ing gear can be used more successfully at high 
speeds, since the intensity of self noise is lower 
in supersonic frequencies than in the sonic, and 
since the high directivity of an echo-ranging 
transducer enables it to discriminate against 
much of the ambient noise. Even so, high noise 
levels at speeds of 20 knots or more make effec- 
tive echo ranging almost impossible with 
earlier gear, not streamlined. Newer gear, with 
the hydrophone housed in a streamline dome, 
can be used at 20 knots, but echo ranges at 
such speeds are much reduced. 

Ambient noise is unaffected by the speed or 
design of the ship, being determined by oceano- 
graphic conditions. Because much of it is 
caused by wave motion, it increases with in- 
creasing sea states. In shallow water, the am- 
bient noise level may be raised by snapping 
shrimp, which produce a steady clatter of 
sound in both sonic and supersonic frequency 
bands. Cooperative studies, made by UCDWR, 
CUDWR, and the Naval Ordnance Laboratory, 
have shown that shrimp noise can always be ex- 
pected in tropical and subtropical areas when- 
ever the water is less than 30 fathoms deep 
and the bottom is rock, coral, or stony. Shrimp 
noise is only one of many sounds of biological 
origin, but it is uniquely important because it 
is omnipresent in certain areas. Other bio- 
logical sounds come and go, continue for sec- 
onds or minutes and stop, but the shrimps 
snap on through day and night. Their clicking 
claws are consequently important not only to 
submariners who like noisy areas, but also to 
the designers of acoustic mines and other sonar 
devices which are triggered by sound. 


SCIENTIFIC DATA SECURED BY NDRC AND THE NAVY 


131 


Almost all noises are “white” ; they are, that 
is, spread over a wide frequency band. Some, 
like the sound of shrimp, have spectra with pre- 
dictable slope, but they are rarely peaked at 
any one frequency or narrow-band frequencies. 
Noise concentrated in a few frequencies is 
ordinarily caused only by the activity of other 
ships, or by industries or other human activi- 
ties in harbors. 

Masking by Noise 

As has been remarked, the masking, or 
“drowning out” of one sound by another is a 
matter of common experience. Some of the laws 
governing it were known before the war, but 
specific data and even some general studies 
were needed. 

The recognition of one sound in the presence 
of another depends not only upon the intensity 
of the two sounds, but also upon their spectra. 
If their spectra are identical, only the louder 
will be heard ; if it is to be distinguished from 
the other, it must be appreciably louder. But if 
one sound has a definite pitch, while the other 
has a wide spectrum, the one may be heard even 
when its intensity is lower than that of the 
other. The use of bugles to transmit signals 
above the roar of battle was based on this fact. 

This is an example of what may be called the 
filter property of the ear. It is capable of hear- 
ing many simultaneous sounds of widely dif- 
fering intensities, and of distinguishing one 
from the other. So long as the sounds are mark- 
edly different in frequency, they will not mask 
one another unless one has a deafening inten- 
sity. Only when two or more are concentrated 
within a narrow band of frequencies (about 
40 c) will they interfere with one another. 

In echo ranging, consequently, recognition of 
an echo (a relatively pure tone) depends upon 
the intensity of the background sound in a 40-c 
band centered at the echo frequency. If the 
echo is louder than other sounds in that band, it 
will be heard. If it is fainter, it will be masked. 
Shifts in echo frequency caused by movement 
of a target toward or away from the echo-rang- 
ing vessel will not affect the ease with which it 
can be recognized against a background of 
noise, for noise has such a relatively smooth 
spectrum that its intensity in any series of ad- 


jacent 40-c bands is approximately the same. 
When the echo length is that commonly used 
(about 200 msec), the echo can just be heard 
if it is equal to the noise in a 40-c band. Shorter 
echoes must be louder in order to be heard. 

In listening, even when the signal is spread 
over a band of frequencies as broad as that of 
the noise, recognition usually depends upon 
perception of those signal frequencies which 
are louder than the noise within 25 c of them. 
It follows, then, that if the slope of the signal 
spectrum closely parallels that of the noise 
spectrum, detection of weak signals will be dif- 
ficult. But if the signal spectrum is peaked at 
some particular frequency, the signal may be 
recognized at long ranges because of a squeak, 
whistle, or groan which rises clearly above the 
background. It is interesting to note that de- 
tailed study of these phenomena has verified 
many of the common phrases used to describe 
them. 

It is the filter property of the ear which 
makes possible the aural detection of signals 
which could never be recognized if they were 
presented visually (with cathode-ray oscillo- 
scope, range recorder, etc.). With all methods 
of visual presentation thus far devised, every 
sound admitted to the receiver is equally effec- 
tive in masking the signal. If the signal is al- 
ways of the same frequency or frequencies, the 
efficiency of visual presentation can approach 
or even exceed that of aural presentation, since 
it is then possible to filter out mechanically all 
background noise except that at or very near 
signal frequency. But the spectra of ships and 
submarines are extremely broad, or else peak at 
varying frequencies. Even the echoes heard in 
echo-ranging receivers change in frequency as 
the target moves toward or away from the 
echo-ranging vessel. Consequently the ear, 
which is able to ignore virtually all sounds ex- 
cept those within 25 c of the signal to which it 
listens, no matter what the signal frequency, is 
ordinarily more effective in detecting faint sig- 
nals than is the eye or any recording device. 
The range recorder is an exception, since the 
study of its permanent record of previous pings 
often reveals details that were overlooked at 
the time. This study can be made by the opera- 
tor as he listens to the later pings. 


132 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


Reverberation Studies 

In listening, the background over which the 
signal must be heard is always noise. In echo 
ranging, the dominant background may be 
either noise or reverberation. 

Reverberation is the sound of many small 
echoes returned by myriads of small sound 
scatterers at the surface, in the volume of the 
water, and at the bottom. It differs from noise 
because it is an almost pure tone (if the ping 
is of constant frequency), and because it is 
generally strongest immediately after the ping 
is emitted and therefore diminishes with time 
(range) . 

This diminution is always observed, but it is 
not regular. Reverberation intensities fluctuate 
widely and rapidly, and though the decay of 
average reverberation intensity may sometimes 
be plotted as a smooth curve, the slope of that 
curve depends on many things and varies mark- 
edly from time to time. Usually the curve is far 
from smooth, being marked by humps and 
peaks at various ranges. But always, since the 
reverberation weakens with range, it must 
sooner or later fall below the constant level of 
the background noise. So long as the reverbera- 
tion is louder than the noise, it is said to be 
dominant, since it is then the sound which tends 
to mask weak echoes. When the reverberation 
is weaker than the noise, the noise is dominant 
and the reverberation becomes unimportant. 

Since reverberation may frequently mask 
echoes at short and intermediate ranges, one of 
the first programs undertaken by NDRC 
scientists was a study of the variation of rever- 
beration. In this study, many kinds of trans- 
ducers, operating at frequencies of from 10 to 
80 kc, and transmitting pings of varying 
length, were used. Some work was initiated 
with frequency-modulated pings and with ping 
lengths as short as 1 msec. Most of the routine 
work, however, was done with longer pings at 
24 kc. Although virtually nothing was known 
about reverberation at the outset of these in- 
vestigations, enough was discovered during the 
war to permit improvement of many opera- 
tional procedures and to indicate possible solu- 
tions for some design problems. Most of the 
work was done at the San Diego laboratory, al- 


though it was guided both by the earlier re- 
search of the British and by valuable assistance 
and suggestions from the Bureau of Ships, the 
Sonar Analysis Group, and the publications of 
other laboratories interested in the develop- 
ment and improvement of sonar gear. 

It is difficult, and perhaps impossible, to 
write a brief description of the reverberation 
studies without oversimplification. Reverbera- 
tion levels depend upon even more variables 
than echo levels ; they are affected by the direc- 
tivity of the gear, the length and frequency of 
the ping, and by all of the oceanographic fac- 
tors known to affect sound transmission. Their 
analysis has led to such disparate activities as 
photographing the ocean bottom, calculating 
the target strength of fish, and studying the 
daily life of plankton. 

Types of Reverberation 

It has been possible to identify reverberation 
originating at the surface, in the volume of the 
water, and at the sea bottom. When an echo- 
ranging projector is near the surface, the first 
crash of reverberation comes from the surface. 
The average intensity of surface reverberation 
decreases rapidly with range and soon sinks be- 
low that of volume reverberation. Bottom re- 
verberation is not heard in deep water but in 
shallow water it is returned as a burst of sound 
from the range at which the beam hits the bot- 
tom. Thereafter the strength of the bottom re- 
verberation falls off fairly rapidly. 

To a sonar operator, of course, the various 
kinds of reverberation are one, since they all 
sound much the same and are mixed together 
in the rolling, ringing sound that he hears in 
the first few seconds after the ping. But their 
separation in the laboratory has led to a better 
understanding of the causes of reverberation. 
Thus, surface reverberation has been found to 
increase with sea state and to be influenced by 
the vertical temperature structure of the ocean. 
Bottom reverberation depends upon the charac- 
ter of the bottom, being weakest over mud and 
strongest over rock. It, too, is affected by tem- 
perature gradients. 

Volume reverberation is not so well under- 
stood. Surface reverberation is probably the 
product of scattering by entrapped air bubbles 


SCIENTIFIC DATA SECURED BY NDRC AND THE NAVY 


133 


and by the irregularities (waves) of the sur- 
face itself. Bottom scattering, similarly, is 
caused by irregularities of structure and com- 
position at the bottom i the greater the irregu- 
larity, the louder the reverberation. But how to 
account for volume reverberation? Some of it 
comes from fish and seaweed, certainly, but 
these are neither so abundant nor so evenly dis- 
tributed as to account for all the observed vol- 
ume reverberation. It may be produced by the 
scattering action of small organisms, but this 
hypothesis encounters difficulties. 

Out of reverberation studies has come one 
important scientific discovery. Even in deep 
water, the volume reverberation does not al- 
ways decrease regularly with range, but may 
have a crescendo at relatively long ranges. It 
has been found that this is caused by a deep 
oceanic layer, in which the population of small 
organisms, called plankton, is very much higher 
than in shallower or deeper layers. These 
organisms perform a daily migration, so that 
during daylight hours, the layer is at a depth 
of 900 to 1,200 ft. In the evening they move to- 
ward the surface, only to return to depth in 
the morning. This ECR-layer, as it has been 
called, has been traced over a wide area of 
ocean off the coast of California, though its 
boundaries have not been definitely located. 
Scattered reports indicate that it is also found 
in other parts of the ocean. 

The precise mechanism connecting the plank- 
ton and the reverberation is not known. The 
simplest idea, that the small organisms them- 
selves scatter sound, may be correct, but this is 
not very probable. It may be that fish feed on 
the plankton, and that they are the immediate 
cause of the scattering, but this hypothesis 
again encounters difficulties. Finally, it may be 
that the plankton generate gas bubbles. A great 
deal of work remains to be done on the ECR- 
layer, which may result in conclusions impor- 
tant not only to the Navy, but also to marine 
biology and the fishing industry. 

Some very important conclusions about re- 
verberation levels have been established defi- 
nitely. Other things being equal, reverberation 
decreases with increased projector directivity. 

It increases with increased power output and 
with increased ping length. This knowledge has 


been important in the design of echo-ranging 
equipment. Its application is not simple, how- 
ever, for any decrease in power output lowers 
not only the reverberation level but also the 
echo level. The relationship between the two 
remains unchanged. Second, the only known 
way to increase directivity without building 
unpractically large projectors is to raise the 
ping frequency. And since the attenuation in- 
creases rapidly with increase of frequency, the 
maximum range may not increase. Other diffi- 
culties multiply if the directivity is greatly in- 
creased. Finally, although it is possible to re- 
duce ping lengths to extremely small values 
without affecting echo levels, a short ping is 
more difficult to hear. Over a considerable 
range of ping lengths, these two effects just 
about balance each other. Very long pings are 
disadvantageous because the increase in audi- 
bility stops at about 200 msec. Very short pings 
are also disadvantageous because their audi- 
bility decreases more rapidly than the rever- 
beration level. 

These questions of audibility are discussed in 
greater detail in following text. 

Masking by Reverberation 

Reverberation is important for two reasons. 
First, it provides a sonar operator with a kind 
of acoustic reference for the detection of dop- 
pler effect in echoes. Since it is composed of 
many small echoes from scatterers which are 
practically stationary, the operator who hears 
an echo of a different pitch knows that his tar- 
get is moving. If the echo pitch is higher than 
that of the reverberation, the target is moving 
toward him ; lower pitch means that the target 
is moving away from him. If the pitch is the 
same, the target is either motionless or is mov- 
ing in a direction that neither opens nor closes 
the range. Serving as an omnipresent refer- 
ence, reverberation makes the detection of 
slight pitch changes possible. 

The second reason for reverberation’s im- 
portance is on the opposite side of the ledger : 
it may make detection of the echo completely 
impossible. It is the dominant background at 
short and intermediate ranges in deep water, 
and is frequently the dominant background at 
all ranges in shallow water. Or, to put it in an- 


134 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


other way, it then is louder than the amplified 
noise, so that if anything masks the echo, re- 
verberation will be that thing. 

Unless the target is moving, the frequency 
of the reverberation will be the same as that of 
the echo. This means that the filter property of 
the ear cannot help to distinguish the echo of a 
stationary target from the reverberation. To 
be heard, the echo must have an intensity much 
greater than the average intensity of the fluctu- 
ating reverberation background ; a weak echo is 
masked. If the target is a floating mine case, 
for instance, its target strength is low and its 
echo is weak. Even with no reverberation at all, 
the echo would usually be masked by noise at 
ranges greater than a few hundred yards ; with 
the reverberation heard in a constant frequency 
echo-ranging receiver in the first second after 
a 100-msec ping, the echo cannot be heard at all. 

For any kind of mine detection, therefore, 
the reverberation must be reduced. With con- 
stant frequency gear, only three methods, pre- 
viously mentioned, are possible. The first of 
these, reducing the power output, is futile, since 
echo strength will suffer as much as reverbera- 
tion. The second, increasing the frequency (and 
so the directivity) of the gear, is only slightly 
more practicable. An increase of attenuation 
accompanies increase of frequency, and since 
present mine-detection gear cannot hope to de- 
tect targets at ranges greater than 1,000 yd, 
some increase of attenuation can be tolerated. 
But unless the sonar is mounted on a pier or 
similar steady platform, too much increase in 
directivity will make it virtually impossible to 
maintain the projector on the bearing of the 
target. Operating such a sonar on a ship is like 
trying to use a high-power telescope without a 
tripod. Finally, an extremely short pulse can 
be used. Since very short pulses have wide spec- 
tra, the filter property of the ear is of no ad- 
vantage in their detection. Therefore, a visual 
presentation of the echo can be used effectively. 
This enables the operator to see extremely 
short echoes which he could never hear. Ex- 
treme reduction of ping length produces a 
great reduction in reverberation levels. 

Target motion makes easier the detection of 
echoes over reverberation. When a target is 
moving toward or away from an echo-ranging 


vessel, its echo has a frequency higher or lower 
than that of the reverberation. This doppler 
effect can shift the echo 50 c or more away from 
the reverberation frequency, and then the echo 
may be heard even if its intensity is less than 
that of the reverberation. The ear is again able 
to center its attention on the echo, and high 
reverberation is not necessarily masking. This 
can be described in terms of the operator’s sen- 
sations. The echo from a stationary target is 
heard as an unusually loud part of the rever- 
beration. The echo from a rapidly moving tar- 
get is heard as a separate sound of different 
pitch. This fact has obvious operational im- 
portance to submariners. When they are oper- 
ating in shallow water over a rocky bottom, or 
under any conditions of high reverberation, 
they know that they may be undetected by echo 
ranging so long as they stop, or at least avoid 
moving rapidly toward or away from the 
searching vessel. If, however, they turn di- 
rectly toward the enemy and increase their 
speed, they know that they may betray them- 
selves with echoes that shriek through the re- 
verberation like a police whistle through traffic 
noise. If they turn directly away from the 
enemy and increase their speed, their echoes 
are even more audible, since down doppler is 
more easily heard than up doppler. 

Many of the phenomena described in this sec- 
tion on masking were not generally recognized 
at the beginning of World War II, although the 
use of doppler to determine target motion had 
already become part of Navy doctrine. The 
work of NDRC groups at UCDWR and BTL 
was not only directed toward the analysis of 
this complex problem, but toward the acquisi- 
tion of numerical data. This was used in at- 
tempting to strike a balance in evaluating the 
importance of the different aspects of the prob- 
lem. 


8 3 ' 4 Application of Data to Gear 

Basic research expenditures are a capital in- 
vestment subject to amortization over a long 
period of time, rather than overhead entirely 
chargeable to current operations. During 
World War II, this economic fact was some- 


SCIENTIFIC DATA SECURED BY NDRC AND THE NAVY 


135 


times obscured, for there was no time to realize 
full returns on the investment. Lack of time 
also affected the conduct of research programs, 
since they were necessarily planned to give the 
earliest results, rather than the most valuable 
results. 

It is to be anticipated that the underwater 
sound data accumulated during the war will 
ultimately exert a considerable influence on the 
design of sonar gear and may lead to the de- 
velopment of new types. Even during the war, 
although many operations, both naval and in- 
dustrial, had to be based on existing types and 
designs of gear, some applications to the de- 
sign of new gear were made. 

Thus, when the development of countermeas- 
ures for the enemy’s acoustic torpedoes became 
urgent, it was obvious that the acoustic proper- 
ties of wakes would determine the success or 
failure of these devices. Knowing the sound 
output of ship screws was also essential. There- 
fore basic research on the properties of wakes 
became a high-priority task assigned to 
UCDWR. The urgency of the task is illustrated 
by the fact that, on orders from CNO, the de- 
parture of a fully loaded carrier [CV] was de- 
layed so that its wake and sound output could 
be studied. The data accumulated by these 
studies were used not only for countermeas- 
ures, but also in the design of our own acoustic 
torpedoes. These measurements were among 
the most difficult that NDRC was called upon to 
make and the haste with which they had to be 
carried out makes it highly desirable to initiate 
a program to study the same problem more 
carefully. 

Data on biological noise were used by the 
Bureau of Ordnance in the design of acoustic 
mines. Development of prosubmarine devices 
(NAC and NAD beacons, described later) was 
based on data concerning the sound output of 
submarines, and on the results of psychoacous- 
tic research. NDRC studies of reverberation 
affected the design of small-object detection 
gear and studies of refraction were important 
in devising a system for correcting the read- 
ings of depth-determination gear under varying 
temperature conditions. 

Harbor defense was also aided by NDRC 
scientists who made a number of expeditions to 


various harbors of the continental United 
States and the Hawaiian Islands for the pur- 
pose of studying background noise, transmis- 
sion conditions, currents, and bottom topog- 
raphy and character. On the basis of these 
studies, NDRC was able to assist the Navy in 
preparing recommendations for the location 
and operation of underwater sound equipment. 
Some of the men who had been engaged in the 
expeditions later cooperated with the UCDWR 
Publications Group in preparing the first draft 
of an official Navy manual explaining the ef- 
fects of oceanographic conditions on the opera- 
tion of harbor defense echo-ranging and lis- 
tening devices. 

This is certainly not a complete list of the 
effects of basic research on equipment design 
during the war. But it is true that the major 
use of the data was in the modification of doc- 
trine concerning existing types of gear. Both 
tactical and strategic plans were affected. 


835 Prediction of Maximum Ranges 

As soon as tests had shown that maximum 
echo ranges were extremely variable and that 
they were influenced by the vertical tempera- 
ture structure of the ocean, work was begun on 
the development of a range-prediction method. 

The need for some method was evident. With- 
out some way of forecasting the maximum 
range on a submerged submarine, echo-rang- 
ing screens were greatly handicapped in their 
work of protecting convoys. With such an esti- 
mate, they could space available antisubmarine 
vessels most effectively for the defense of a 
convoy, for the detection of an escaping sub- 
marine, or for the establishment of a patrol 
across a narrow strait or channel. Knowledge 
of seasonal and local variations could be 
utilized in planning the safest routes for con- 
voys. 

As anyone familiar with experimental 
studies of sound transmission might guess, it 
was impossible to work out a perfect method of 
range forecasting immediately. Even now the 
prediction system has many shortcomings 
which can be remedied only as more is learned. 
Some margin of error must be expected to con- 


136 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


tinue indefinitely, since the problem is very 
similar to that of weather forecasting. But the 
present range-prediction methods are a great 
improvement over the first fumbling efforts, 
which frequently were grossly inaccurate, 
overly complicated, or both. 

Prediction Methods 

The first method of range prediction was 
simple enough — too simple, in fact. Based on 
the assumption that ranges always extended 
just to the shadow boundary shown on ray 
diagrams, the first official manual which NDRC 
helped to prepare for the Navy predicted only 
the assured range (maximum range on a sub- 
marine at the depth where the maximum range 
is shortest), and that for only three types of 
temperature structure. Simple tables were 
used, together with specific instructions for de- 
termining from a bathythermograph slide the 
proper table to be used. 

Many slides, unfortunately, did not fit these 
simple rules, and in these cases no prediction 
could be made. Even when the slides did seem 
to fit, a further disadvantage of the method was 
that only the assured range could be estimated. 
Therefore this first method was modified, and a 
special refraction slide rule was issued to anti- 
submarine vessels. The use of the slide rule per- 
mitted somewhat more accurate predictions but 
a considerable amount of training was needed 
before an operator could calculate a ray dia- 
gram showing the theoretical extent of the 
sound field and the maximum range for various 
target depths. The calculations were time-con- 
suming and liable to mistakes. They required 
concentration, and it was expecting too much 
of the sound operator or sound officer to ask 
him to perform them at sea. 

Finally, as experimental data accumulated, it 
became evident that even this complicated pre- 
diction method was less accurate than it should 
be. It was based solely on the limits of the 
sound field as determined by refraction theory 
and so failed to take into account many of the 
factors now known to have a profound influ- 
ence on the maximum echo range. Predicted 
ranges were usually too long because it was 
assumed that the intensity of sound from an 
echo-ranging projector would drop 80 or 90 db 


(as calculated from the ray diagram) before 
the echo became too weak to be detected. This 
last assumption is almost never justified. The 
effects of reverberation and ambient and self 
noise were ignored in the method. 

The present prediction method contains two 
different procedures, one for deep water, and 
one for shallow water. Under certain condi- 
tions, the method used in deep water may be 
used in shallow water as well. When these con- 
ditions are not found, however, the problem of 
range prediction in shallow water is so compli- 
cated by bottom reflection and reverberation 
that it must be solved by entirely different 
means. 

The present system of prediction used in 
deep water differs radically from previous ones 
in that it attempts to predict the range at which 
the intensity of the signal has dropped to the 
point where a returning echo will just be de- 
tected (i.e., heard 50 per cent of the time) 
through the noise tending to mask it. Thus the 
range tables now in use are based not only upon 
transmission measurements but also upon 
studies of noise, reverberation, and recogni- 
tion. Even so, they give only approximate val- 
ues ; there can be little doubt that the systematic 
study of sound transmission will produce new 
methods which will be both more accurate and 
less difficult to use. 

The present system of prediction used in 
shallow water is already obsolete. When the 
method was first formulated, very little was 
known of transmission losses in shallow water 
and not very much was known about bottom re- 
verberation. Since March 1944, when the last offi- 
cial manual for antisubmarine vessels was pub- 
lished, much more work has been done in shal- 
low water. Consequently, it is now possible to 
make rough generalizations about transmission 
over different kinds of bottoms. These have 
been used in the preparation of manuals for 
submariners, who are acutely interested in 
areas of poor sound conditions. Since the end 
of World War II, additional progress has been 
made by UCDWR operating under a direct con- 
tract with the Bureau of Ships, and there is 
some hope that future methods of forecasting 
for shallow water may be even more reliable 
than those for deep water. 


SCIENTIFIC DATA SECURED BY NDRC AND THE NAVY 


137 


Bathythermograph Data 
Applications 

When it became apparent in 1944 that enough 
accurate information had become available to 
permit extensive operational use of predicted 
ranges, drafts of tactical rules for using range 
predictions in antisubmarine warfare were for- 
mulated by the Sonar Design Section of the 
Bureau of Ships, in collaboration with NDRC 
groups and the officers responsible for tactical 
doctrine. 

During the last 18 months of World War II, 
consequently, dial settings of sonar gear were 
determined in part by sound ranging condi- 
tions. Both the keying interval (time between 
successive pulses) and the ping length, for 
instance, were based on the local conditions 
revealed by the bathythermogram. Escort, 
search, and scouting plans for antisubmarine 
vessels were also based on the predicted maxi- 
mum range, with ship spacing and choice of 
search procedure being subject to carefully for- 
mulated official doctrines. Since not all escort 
vessels are equipped with bathythermographs, 
signals were devised for sending information 
on sound conditions from one ship so equipped 
to all the others operating with it. 

Submarines also made increasing use of 
oceanographic information, and particularly of 
BT observations. Since lowering a small in- 
strument overboard from a submarine was not 
feasible, a special submarine BT was developed 
by WHOI. With a temperature-measuring ele- 
ment fastened rigidly to the outside of the 
boat and connected to a recording element in- 
side the pressure hull, the submarine BT made 
a continuous record of the temperature of the 
water at all depths through which the subma- 
rine moved. This record had many uses, many 
of which were suggested by submarine person- 
nel after bathythermographs had become stand- 
ard gear. 

First of all, of course, the BT record is one 
of the submariner’s best guides to sound con- 
ditions at all depths. Using tables and charts 
similar to those published for antisubmarine 
vessels, he can determine the areas and depths 
at which he is least likely to be detected by 
sonar gear and can use this knowledge in de- 


termining tactics of approach, attack, and eva- 
sion. Equally important, however, is his use of 
the submarine BT as a hydrometer. Since the 
density of sea water varies markedly only with 
changes of temperature and salinity, and since 
there are great areas of the oceans in which 
salinity changes are so slight as to be unim- 
portant, the BT record is usually a reliable 
indication of the change of density with depth. 
Even when marked salinity gradients are pres- 
ent, they are frequently accompanied by dis- 
tinctive temperature distributions which reveal 
their presence. Toward the end of World War 
II, improved instruments were developed that 
measured salinity as well as temperature and 
automatically computed the density. 

Using the BT, submariners found that they 
could dive more quickly, quietly, and safely; 
they also found that the BT detects and records 
sharp negative gradients (layers of water in 
which the density increases so rapidly with 
depth that a properly trimmed submarine can 
float on them with motors stopped). This kind 
of density layer is easily illustrated by an ex- 
treme example : when water floats on mercury, 
a stone which sinks through the water will float 
lightly on the mercury. Though the density 
changes in the ocean are never so dramatic or 
so abrupt, they can sometimes be used in the 
same way. 

Publications 

Both surface vessels and submarines took 
ever increasing numbers of BT observations 
as World War II continued. These records had 
an immediate value in the estimation of spot 
conditions, but they were also valuable in ex- 
tending naval and scientific understanding of 
conditions in the Atlantic and Pacific Oceans. 
Consequently, all records were saved by forces 
afloat and forwarded to the Hydrographic Office 
for interpretation and filing. As has already 
been remarked, a farsighted policy had initi- 
ated this program of observation by naval ves- 
sels even before the BT had developed into an 
operational necessity. 

NDRC was concerned with the taking and 
interpretation of all BT data. To instruct men 
in the use of the BT and the information 


138 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


it provides, scientists from both WHOI and 
UCDWR were attached to submarine and anti- 
submarine forces. These men aided naval offi- 
cers in supervising the installation and main- 
tenance of BT gear; they were able to explain 
seemingly anomalous sound and diving condi- 
tions by making the most recent scientific in- 
formation available to the Navy; and they were 
able to conduct many valuable tests of ship and 
submarine performance under a wide variety 
of operating conditions. 

Navy Manuals 

The training activities of these scientists 
were facilitated by the publication of new offi- 
cial Navy manuals. Although the preparation 
of these manuals was properly a part of the 
NDRC training program, the technical nature 
of the material made it essential that the manu- 
scripts be written and edited by personnel in- 
timately connected with the scientific program. 
The operational nature of the material made 
close liaison with the operating forces simi- 
larly essential. 

For the preparation of these manuals and 
their illustrations, the Bureau of Ships re- 
quested NDRC to establish a publications 
group. This was done, and the UCDWR em- 
ployed a staff of artists and writers who worked 
in the same laboratory with the scientific staff. 
Liaison with the operating forces was made 
possible by the close cooperation of the Sonar 
Analysis Group and the Bureau of Ships. Con- 
ferences between all concerned in this complex 
project were frequent, and required much 
travel. Groups of San Diego personnel some- 
times worked for periods of several weeks in 
Washington, so that they could have the benefit 
of frequent conferences with naval officers sta- 
tioned there. The published manuals contained 
the simplest explanations (consistent with cor- 
rectness) of the factors determining sound and 
diving conditions, as well as the most recent 
tables and instructions for interpreting BT ob- 
servations and various Hydrographic Office 
charts. 

Hydrographic Charts 

Many of these charts were themselves pre- 
pared by NDRC scientists working in close 


cooperation with officers attached to the Hydro- 
graphic Office. Since all BT records (or copies) 
were forwarded to NDRC laboratories — slides 
from the Atlantic and Mediterranean to WHOI, 
slides from the Pacific and Indian Oceans to 
UCDWR — great quantities of new data on the 
temperature distribution in the oceans were 
made available. By the end of December 1944, 
more than 40,000 slides had been returned from 
the Pacific and about as many from the Atlantic. 
When this new information was added to that 
accumulated before World War II, both by the 
Allies and our enemies, a number of valuable 
aids could be prepared for the Navy. 

Sound, Ranging Charts. Among these aids 
were the sound ranging charts, which combined 
the most recent findings of underwater sound 
research with all available oceanographic infor- 
mation to show predicted sonar conditions in 
many areas of active submarine and antisubma- 
rine warfare. These charts went through several 
editions as knowledge of the effect of tempera- 
ture conditions on maximum echo ranges became 
more precise. They were disseminated widely 
through the Navy, and were used in the routing 
of convoys and in the planning of antisubma- 
rine activities. The two sound schools included 
lectures on these charts in their curricula. These 
lectures were sometimes delivered by NDRC 
personnel, and were always planned in close 
consultation with it. 

Bottom Sediment Charts. Equally important 
were the bottom sediment charts, which were 
rushed into production when German subma- 
rine activity along the Atlantic and Gulf coasts 
demonstrated forcefully the importance and 
variability of sound conditions in shallow 
coastal waters. The dependence of echo ranges 
on bottom type in shallow water was deter- 
mined by the only available method — theory. 
NDRC engaged marine geologists (members of 
a very specialized profession) who brought to- 
gether all available charts and studies of each 
area, collated all notations of bottom type, and 
prepared new bottom sediment charts for pub- 
lication by the Hydrographic Office. Later, as 
American submarines pushed nearer Japan, 
similar charts were prepared for the most im- 
portant and active areas of the Pacific. Other 
charts, requested in connection with amphibi- 


A PEACETIME RESEARCH PROGRAM 


139 


ous operations, were also prepared. Coopera- 
tion with the Joint Army-Navy Intelligence 
Service was an essential element in the success 
of this work. 

Submarine Supplements. For submariners, 
in addition to official BT manuals and bottom 
sediment charts, a series of Submarine Supple- 
ments to the Sailing Directions was prepared 
by a separate NDRC group and published by 
the Hydrographic Office. These supplements 
included not only information on sound and 
diving conditions, but also charts and descrip- 
tions of wind and water currents, of bottom 
topography and character, of salinity gradi- 
ents, and of transparency conditions. Three 
NDRC groups at WHOI, SIO, and UCDWR 
cooperated with the Hydrographic Office and 
the Sonar Analysis Section in their prepara- 
tion. A special group of writers and cartog- 
raphers was established at UCDWR under the 
supervision of a geologist on leave from the 
Geological Survey of the Department of the In- 
terior. They maintained close contact with all 
the scientists whose research had made possible 
the preparation of these very comprehensive 
atlases of the ocean areas most important dur- 
ing World War II. 

The reception accorded these supplements by 
the submarine forces indicates that all ocean 
areas should ultimately be described in a sim- 
ilar manner. This is a major peacetime project 
for the Hydrographic Office, and will require 
an expansion of its staff and facilities. 


84 A PEACETIME RESEARCH PROGRAM 

Research has been defined as the production 
of something whose specifications cannot be 
written in advance of completion. Provided it 
is recognized that ideas are usually the most 
valuable product of research, this definition is 
not bad. It is obvious, however, that it refers 
primarily to the construction of apparatus 
whose function is predetermined, although its 
construction and capabilities are indeterminate. 

The activities described as research are so 
varied that many definitions are possible. An- 
other definition asserts that pure research is an 
activity without visible practical objective. This 


definition is unpalatable to many administra- 
tors, but embodies certain well-established 
truths, for it has been found by experience that 
the most valuable practical results often arise 
out of work that was done without conscious- 
ness of the practical objective. 

This can be illustrated by two well-authenti- 
cated instances. Oliver Lodge was very active 
in the early study of radio waves, and made 
valuable contributions to knowledge of their 
properties and means for his generation. He 
later stated that he had no thought of their use 
for communication purposes, and that news of 
Marconi’s application of them came to him as a 
complete surprise. 

In other cases, the general objective may be 
visible to the research worker, but appear vi- 
sionary to the layman. Thus, during World 
War I, Ernest Rutherford was asked to help 
develop underwater sound gear. He refused, 
saying that his work on atomic disintegration 
was much more important. At that time, few 
scientists could have foreseen that Rutherford’s 
work would lead to military application within 
a generation and the layman’s incredulity would 
have occasioned no surprise. 

These definitions and anecdotes could be mul- 
tiplied. They serve only to vivify an abstract 
truism: research is an exploration of new and 
unknown areas. The task of Division 6 of 
NDRC at the beginning of World War II was 
the development of an organization for the ex- 
ploration of underwater sound. A similar prob- 
lem confronts the Navy at the present time. 
The NDRC organization is now scattered. The 
work begun by it is incomplete, and the con- 
ditions under which the work is to be completed 
are different. It is appropriate to conclude this 
chapter on wartime research with suggestions 
as to an organization that can continue per- 
manently. 

At least three kinds or levels of research can 
be distinguished. They are : 

1. The development of gear to perform speci- 
fied functions. The projects of this program 
have definite objectives and definite lines of 
progress toward them. 

2. The research supporting the development 
program, by exploring other objectives, other 
lines of progress, and by systematically ac- 


140 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


cumulating basic data on the factors limiting 
the performance of gear already constructed 
or under development. 

3. The pure research, whose objectives may 
be difficult to define, but out of which the ob- 
jectives of the other two levels will evolve. 

Each of these three levels of research in 
underwater sound should receive support from 
the Navy, but not all in the same manner. 


The Development Program 

It is fairly clear that the development pro- 
gram is of interest only to the Navy and of 
such vital interest that its administration must 
be kept within the Navy’s immediate jurisdic- 
tion. In accordance with established policy, 
this program will consist of two parts: one 
entrusted to naval laboratories staffed by ci- 
vilian scientists, and the other entrusted to 
industrial organizations operating under con- 
tract with the Navy. 

The objectives of this organization must be 
determined jointly by the cognizant bureaus 
and the senior civilian staff of the naval labora- 
tories. The objectives will change as the situ- 
ation develops, necessitating an organization 
that will be responsive to such changes of ob- 
jective. On the other hand, the administration 
must naturally guard against the confusion re- 
sulting from too-frequent changes of objective. 

Each of the smaller parts of the organization 
must clearly understand its mission and its re- 
lation to the major objective. Freedom of deci- 
sion must be allowed, and initiative in accom- 
plishing the mission must be encouraged. Com- 
munication between parts of the organization 
must be possible without congesting the higher 
administrative offices. 

It may not be superfluous to remark that this 
organization will be staffed largely by engi- 
neers, rather than by scientists in the academic 
sense of the title. It is important that liaison 
between this engineering development program 
and the supporting program of scientific re- 
search be close. This can be best accomplished 
by obtaining the services of engineers whose 
professional training is such that they can, on 
occasion, participate actively in the scientific 


phases of research. The present trend in the 
engineering profession is such that this should 
become increasingly possible in the future. 


Supporting Research 

Although the broad objective of this program 
is to support and assist the engineering pro- 
gram just described, it must not be organized 
as a service at the command of the develop- 
ment organization. The immediate missions are 
scientific rather than engineering. The activi- 
ties of this organization should therefore be 
directed entirely by the senior scientific staff 
of the naval laboratories. Frequent changes of 
objectives must be avoided, for the scientific 
process is time-consuming. Frequent changes 
in objective are thus likely to prevent all prog- 
ress. 

The supporting research will frequently re- 
quire facilities beyond the means of the naval 
laboratories. Examples are the BT, wake, and 
ship sound programs mentioned in the earlier 
pages of this report. Although refraining from 
participation in directing such work, the cog- 
nizant bureaus and even the Navy must be 
sufficiently informed of its nature and value so 
that they will freely make available the neces- 
sary facilities. The fact that such facilities were 
provided by the Navy even in time of war 
indicates that this information and willingness 
to participate is already widespread. It cannot 
be too strongly emphasized, however, that such 
a policy of participation in scientific programs 
on the part of the bureaus and the Navy is 
dictated by self-interest. 

As has been said, the objectives of these pro- 
grams are such that the layman cannot prop- 
erly assess their value to the Navy, and hence 
should not participate in their direction. None- 
theless, the values involved are so specifically 
naval that outside organizations cannot be ex- 
pected to support them financially. This is true 
even of some of the programs that do not re- 
quire facilities beyond the means of the naval 
laboratories. 

The calibration stations furnish one example 
of such an activity. Since their mission is one 
of careful measurement, unbiased by any per- 


A PEACETIME RESEARCH PROGRAM 


141 


sonal interest in the result, they must be main- 
tained and supported entirely by the Navy. 

Another example is a consulting and fact- 
finding organization, which will assist in the 
preparation of operational plans and doctrine. 
Although this is traditionally a function of the 
commissioned personnel, the technical nature 
of modern warfare makes some of the problems 
scientific rather than military or even engi- 
neering. The limitations imposed by natural 
laws on the performance of gear and its opera- 
tion so as to obtain optimum results — these are 
problems on the level of the supporting re- 
search program. 

Although all such activities must receive their 
financial support from the Navy, it is possible 
that universities or other scientific organiza- 
tions can be induced to direct them under con- 
tracts with the Navy Department. In general, 
however, the reluctance of civilian organiza- 
tions to assume such responsibilities will in- 
crease in direct proportion to the value of the 
work to the Navy. This should not be consid- 
ered a reproach to these organizations : in many 
cases their charters are specific in formulating 
their objectives in such terms that a wide in- 
terpretation is necessary before they can justi- 
fiably engage in specifically naval enterprises. 
It should be added that almost all of the re- 
search performed by universities during the 
war, under NDRC auspices, was of this nature. 
It was justified by the emergency, but in peace- 
time, the universities cannot continue to carry 
this work. 

The Navy must therefore be prepared to se- 
cure the services of men with high professional 
standing. The difficulty of competing with aca- 
demic institutions in this field has often been 
stressed, but until now, these latter have not 
faced serious competition. 


Pure Research 

The social and economic value of pure re- 
search is no longer a subject of argument. The 
names of many of the great men in this field 
have entered so basically into our technological 
language that they are no longer even capital- 
ized : e.g., volt (Alessandro Volta) , ohm (George 


Simon Ohm), farad (Michael Faraday), henry 
(Joseph Henry). The objectives toward which 
these men were working were quite incompre- 
hensible to contemporary laymen. Often they 
remain so today, even though the layman has 
had to learn their names in order to purchase 
household appliances. The' engineer has some- 
what greater comprehension for these past 
achievements, but his professional necessities 
prevent him from being fully aware that the 
same process is continuing today, and at an 
accelerated pace. 

Traditionally, the universities are the home 
of pure research. Their financial endowment, 
according to this same tradition, comes as a 
gift from private individuals. These traditions, 
together with that of academic freedom, have 
insured the continuation of pure research, no 
matter how unclear its objectives might be. The 
only necessity was that someone find the prob- 
lems sufficiently interesting to work on them 
despite the small financial return to himself. 

The traditions of the industrial research lab- 
oratory were largely established by Thomas A. 
Edison. He found such a large accumulation 
of the results of pure research that there seemed 
no need for more. In fact, his work and that 
of his associates was almost entirely develop- 
ment. Edison was the first to undertake the 
systematic exploitation of scientific results, and 
worked under conditions that may be compared 
to those in a virgin forest. By comparison, 
present-day development work is the harvest- 
ing of plantations; hence the necessity for sci- 
entific research directly supporting every de- 
velopment program. The research conducted in 
academic organizations may be compared to 
the spontaneous growth in previously unfor- 
ested areas — an obviously uncertain process. 
The analogy should not be labored, however. 

These traditions are changing. The large in- 
dustrial laboratories have found it advisable 
to encourage pure research, as well as to estab- 
lish development organizations and their sup- 
porting research. The achievements of Irving 
Langmuir at the General Electric Research 
Laboratory and of C. J. Davison at the Bell 
Telephone Laboratories have been recognized 
by the award of the Nobel Prize. 

The reasons for the support of pure research 


142 


FUNDAMENTAL STUDIES OF UNDERWATER SOUND 


by industrial concerns are various; altruistic 
motives should not be excluded, but there are 
others. The professional reputation of both 
laboratory and staff depends in large measure 
on its publications, and security problems exist 
even in industry. The publication of pure re- 
search presents fewer problems than does that 
of results having more immediate objectives. 
The professional reputation of the laboratory 
is important, not merely for prestige and ad- 
vertising, but because of the professional chan- 
nels of communication which it opens. The 
influx of intelligence through these channels is 
of extreme value. Moreover, it is very difficult 
to obtain first-class scientific personnel for a 
laboratory whose professional reputation is 
small. The professional scientist is accustomed 
to place a very considerable financial value on 
such matters, as well as on an environment in 
which pure research flourishes. Finally, al- 
though the financial return on investment in 
pure research is speculative, it is occasionally 
unexpectedly large. 

Many of these reasons are equally cogent in 
fixing the policy of a government agency, and 
the altruistic motives should be given greater 
weight. It cannot be too strongly emphasized 
that, while the objectives of pure research are 
obscure, experience shows that its value is 
enormous. It is no exaggeration to say that our 
present technological civilization would be im- 
possible had it not been for the mathematical 
and astronomical researches of Newton. Fifteen 
years ago, many people were inclined to say 
that the work of Einstein would never affect 
everyday life. Today it would seem very rash 
to make that assertion, and 15 years from now, 
the effects may be appreciable. 

In other words, while the return to the in- 
vestor in pure research may be highly specu- 
lative, the return to society is certain and large. 
This is the reason that has influenced the indi- 
vidual donors of the past to endow universities 
for this purpose. The changing economic state 
of the world is reducing the funds thus made 
available for this important social function; 
the obligation of state and federal governments 
to provide the necessary support is clear. The 
present arguments in Congress and elsewhere 
concern the mechanism of checks and balances 


necessary to make government funds available 
without placing the research under the handi- 
cap of a bureaucratic supervision which might 
stifle initiative. The early obscurity of the ob- 
jective of the most valuable work is such that 
not even the most competent scientist can be 
entrusted with too much authority over the 
work of others. This is the reason for the tra- 
dition of academic freedom in determining what 
problems each man will pursue. 


8AA Summary 

To summarize this rather general discussion 
as it applies to the research policy of the Navy: 

1. It is essential that a certain amount of 
pure research by the staffs of naval laboratories 
be encouraged and adequately supported. 

2. It is essential that professional contacts 
be maintained with research workers in the 
universities and other private laboratories. 

3. It is entirely proper for the Navy to pro- 
vide financial support for pure research in aca- 
demic institutions and it may reasonably an- 
ticipate such an investment to be profitable in 
the long run. 

4. In thus supporting academic institutions, 
the Navy will acquire power over them, and 
thus also the responsibility not to misuse this 
power. 

If and when a general Federal agency for 
the support of research is established, the Navy 
will undoubtedly wish to work through it, and 
delegate the responsibility mentioned in point 4. 
This should not affect the conclusions formu- 
lated in points 1, 2, and 3. 

Specific Fields of Underwater Research 

Any specific proposals for naval research 
programs must presuppose the existence of 
organizations capable of performing the func- 
tions outlined above. In the following, no at- 
tempt will be made to discuss the development 
program. The reasons for this omission will 
be clear from the previous discussion. The 
amount of work that might be done in the way 
of supporting research and pure research is 
very large, and some selection must undoubt- 
edly be made by the scientific administration 


A PEACETIME RESEARCH PROGRAM 


143 


of the naval laboratories and by those other 
agencies within the Navy Department whose 
responsibility is the liaison with academic re- 
search. 

The following list in Table 1 makes some 
pretense at completeness, but it cannot be hoped 
that there are no omissions. However, it in- 
cludes only research 51 that specifically supports 

a More specific suggestions as to needed research will 
be found in Division 6, Volume 7, entitled, “Principles 
and Applications of Underwater Sound.” 


the probable program for the development of 
underwater sound gear and closely allied prob- 
lems. The possibilities for pure research are 
only implicit in the outline. The projects are 
not all of the same kind — some are very de- 
tailed, some very broad ; sqme will require only 
a small staff and few facilities, some can only 
be carried out with the cooperation of the 
Navy. Because of this heterogeneous character 
of the projects, no attempt has been made to 
arrange them in any order of importance. 


Table 1 . Research specifically supporting the development program. 


Data programs Laboratory and Forecasting and 

theoretical problems planning problems 


Calibration stations. 

Sound ranges for measuring the 
sound output of ships. 

Self-noise measurements. 

Target strength measurements. 
Ambient noise surveys. 
Transmission and scattering of 
sound in the sea. 

Acoustic properties of wakes. 
Bathythermograph program. 

Marine geology. 

Marine biology. 

Diving characteristics of submarines. 
Surface waves at sea. 


Electromechanical properties of 
crystals, etc. 

Theory of electromechanical sys- 
tems. 

Generation of underwater sounds 
— wanted and unwanted. 

Cavitation. 

Theory of beam patterns and 
hydrophone arrays. 

Sound absorbing properties of ma- 
terials, including sea water and 
other fluids. 

Velocity of sound in sea water as 
a function of temperature, pres- 
sure, and salinity. 

Theory of the propagation of 
sound in nonideal media. 

The formation of echoes by large 
objects. 

The scattering of sound by 
bubbles and small objects. 

Theory of and experimental work 
on the physical characteristics 
of noise. 

The masking of one sound by 
another. 

Laws of hearing in general. 


Forecasting of oceanographic con- 
ditions. 

Prediction of maximum echo and 
listening ranges. 

Plans for search and attack using 
underwater sound gear. 

Plans of installation of gear on 
shipboard and in harbors. 

Plans for evasive maneuvers and 
use of countermeasures. 


Chapter 9 

TRANSDUCER RESEARCH AND CALIBRATION 

By Robert S. Shankland, Frederick V. Hunt , and Franz N. D. Kurie 


91 MAGNETOSTRICTION TRANSDUCERS 

M ost of the scientific work devoted to the 
production of new tools for subsurface 
warfare involved the type of work commonly 
called development rather than research. De- 
velopment work usually involves the modifica- 
tion and application of known scientific prin- 
ciples and techniques to produce new and useful 
results. Research work, on the other hand, is 
directed toward the establishment of scientific 
principles and increasing the scope and store 
of fundamental knowledge. 

The wholesale concentration of scientific 
manpower during World War II on the devel- 
opment of weapons of war made serious in- 
roads on the unexploited stock of fundamental 
knowledge. It is to the credit of the academic 
scientists that they were able so effectively to 
translate basic science into practice but, to 
borrow a term from oil conservation, the de- 
pletion of our proved reserves of fundamental 
scientific knowledge is a matter for national 
concern. This impairment was aggravated by 
the almost total diversion of academic scientists 
from their normal peacetime research to 
weapon development. 

In the face of this situation the study of the 
science and art of designing and constructing 
magnetostriction transducers provided an ex- 
ception to the rule. A substantial program of 
basic physical research in magnetostriction was 
conducted by three of the Division 6 contrac- 
tors in parallel with a program for the devel- 
opment of transducers for experimental and 
Service use. These agencies included Bell Tele- 
phone Laboratories [BTL], Harvard Under- 
water Sound Laboratory [HUSL], and Colum- 
bia University Division of War Research at the 
U. S. Navy Underwater Sound Laboratory at 
New London [CUDWR-NLL]. As a result of 
this research effort, the fundamental scientific 
base for further development work in magneto- 
striction has been broadened and strengthened 
rather than restricted by the work devoted to 
subsurface warfare. 


The principle of magnetostriction is very old 
but its technological utilization dates from the 
middle 1920’s. In the period following that 
marked by the pioneer work of G. W. Pierce, 
the development of magnetostriction transduc- 
ers as underwater sound projectors was carried 
forward by the staff of the Naval Research 
Laboratory [NRL]. The development lacked, 
however, the impetus that would have been 
provided by a widespread demand for indus- 
trial use and restricted resources prevented 
NRL from exploiting the development fully. 
The lack of an industrial demand arose in part 
from restrictions on the dissemination of in- 
formation imposed in the interest of military 
security and also in part from a lack of suffi- 
cient scientific personnel in industry trained 
to handle the experimental work required “to 
prove in” the potential industrial applications 
of high-frequency sound. It may be remarked, 
incidentally, that the postwar redeployment of 
scientific personnel engaged in these problems 
during World War II may go a long way toward 
increasing the industrial use of ultrasonics 
provided the postwar requirements of military 
security permit a rather free dissemination of 
the results of these scientific studies. 

Magnetostrictive materials, such as nickel 
and nickel-bearing iron alloys, are intrinsically 
stiff and are, therefore, exceptionally suitable 
for the generation of sound waves in liquid 
media, such as water, which are also stiff. Mag- 
netostriction transducers are well adapted for 
use in the frequency range extending from 10 
to 100 kc (and perhaps higher) and can easily 
produce sustained sound waves of intensities 
sufficient to cause cavitation in all ordinary 
liquids. Transducers, or sound projectors, for 
echo-ranging equipment were available and in 
wide use at the beginning of World War II but 
the conversion efficiency of such transducers 
was low, techniques were not available for 
determining their electroacoustic performance 
accurately, and control of uniformity in pro- 
duction was extremely difficult. There was little 
control over the shape of the radiated sound 


144 


MAGNETOSTRICTION TRANSDUCERS 


145 


beam, and the design of the projector itself 
was a matter of experimental trial and intui- 
tion rather than a result of accurate quanti- 
tative analysis. 

The Harvard Underwater Sound Laboratory 
carried on throughout the war a research pro- 
gram devoted to elucidating the fundamental 
factors affecting the performance of magneto- 
striction transducers. As a result of the studies 
of the HUSL group and the collateral investiga- 
tions of the other laboratories engaged in similar 
work, it not only became possible to construct 
improved transducers for sonar and ordnance 
purposes but also to put the problem of design- 
ing such transducers on a sound engineering 
basis permitting calculation of performance in 
advance of construction. 

Analysis of Electromagnetic Coupling 

The fundamental research program on mag- 
netostriction transducers carried out by HUSL 
can be described under three broad headings. 
First of all it was necessary to make a careful 
theoretical analysis of the electromagnetic con- 
version process. Special emphasis was placed 
upon a mathematical analysis of the magneto- 
strictive coupling between the electrical driv- 
ing circuit and the active material of the trans- 
ducer so that this fundamental characteristic 
of the transducer could be described quanti- 
tatively in terms of the magnetic properties of 
the active material and the configuration of the 
electric and magnetic circuit's. This study made 
it possible to draw equivalent electrical circuits 
which would represent the performance of the 
electroacoustical system not only in a qualita- 
tive way but with quantitative precision. 

These equivalent circuits made it possible to 
apply to the transducer design problem the 
wealth of technical information concerning the 
behavior and design of electric transmission 
networks. By computing the performance of 
the equivalent electrical circuit it was possible 
to propose useful alterations in the electric, 
magnetic, mechanical, or geometrical charac- 
teristics of the transducer. This work is closely 
related to the analyses of mechanical vibrating 
systems discussed in following text. It provided, 
however, an independent method of dealing 
quantitatively with the vibrating system of the 


transducer, placing special emphasis on the 
evaluation of the magnetostrictive coupling and 
the corresponding electromechanical conversion 
efficiency. 

An example of the utility of the foregoing 
analysis arose in connection with the considera- 
tion of a novel magnetostriction transducer util- 
izing flexural vibrations. In this case it was 
possible to compute the resonant vibration 
frequencies of the system, the electroacoustic 
coupling coefficient and the expected efficiency 
of the device in several modes of vibration, all 
in advance of constructing the first model. 

Properties of Materials 

It was also necessary to conduct investiga- 
tions and make extensive measurements of the 
magnetic properties of the magnetostrictive 
materials available for use in transducer con- 
struction. Pure nickel remains one of the most 
useful of the magnetostrictive materials for 
transducer construction but its behavior can be 
influenced remarkably by heat treatment and 
mechanical working. In addition to studies of 
nickel of commercial purity, measurements 
were made of the magnetic properties of vari- 
ous alloys including in particular vanadium- 
Permendur (2% vanadium, 49% cobalt, re- 
mainder iron) which proved to have properties 
especially useful in transducers operating with- 
out benefit of an external source of magnetic 
polarization. 

The magnetic measurements made by HUSL 
included initial magnetization curves and ac- 
curate delineation of complete hysteresis loops 
for carefully prepared small samples. In addi- 
tion, special experimental arrangements were 
made for determining accurately the varia- 
tional permeability observed for various steady 
conditions of magnetic polarization. The back- 
ground of experimentation with sample trans- 
ducers, utilizing magnetostrictive materials 
which had received various heat treatments, 
made it possible to confine the magnetic studies 
conducted by HUSL to those materials which 
showed the most promise. 

An extensive investigation was also con- 
ducted by engineers of BTL who used their 
metallurgical facilities to provide specimens of 
many alloys having a wide range of composi- 


146 


TRANSDUCER RESEARCH AND CALIBRATION 


tion. These measurements, which included both 
static and dynamic studies of magnetostrictive 
activity, eliminated many alloys from further 
consideration and provided a very useful body 
of fundamental data on magnetostriction re- 
search. The BTL studies also covered a wide 
variety of heat treatments for the materials 
showing the most favorable magnetostrictive 
properties and provided a guide for establish- 
ing the specifications for magnetostrictive ma- 
terials. 

It may be said that these studies did not 
indicate that any single material is universally 
“best” for the construction of magnetostriction 
transducers. The requirements for an ideal ma- 
terial for transducer construction are inher- 
ently contradictory. High reversible permea- 
bility and high coercive force are both desirable 
but they usually increase and decrease in oppo- 
site directions as the composition and treatment 
of the material are varied. Fortunately, useful 
compromise values may be obtained. 

It is usually desirable to emphasize the high 
reversible permeability of the magnetostrictive 
material and then to compensate for the cor- 
responding low coercive force by providing 
polarization by permanent magnets suitably 
disposed. This suggests that composite mate- 
rials might be used for the magnetic circuit 
and some preliminary experiments were car- 
ried out to explore this possibility. However, 
until improved methods of utilizing composite 
magnetic circuits become available, it will con- 
tinue to be necessary to apply engineering judg- 
ment in the choice of the magnetostrictive ma- 
terial best suited for a specific application. 

Analysis of Vibrating System 

The third major phase of fundamental re- 
search in magnetostriction transducer design 
concerned the analysis of the complex vibrat- 
ing system by which magnetostrictive strains 
are converted into the vibration of a radiating 
surface in contact with the water medium. This 
activity offered many opportunities for inge- 
nuity and invention and, as often as not, the 
detailed analysis followed, rather than pre- 
ceded, the suggestion of a basic design scheme. 
Both the New London Laboratory and HUSL 
conducted active programs of transducer de- 


sign in which various configurations of the 
magnetostrictive material were employed in the 
attempt to secure desirable performance in 
the final transducer. 

Eddy currents constitute one of the most 
serious sources of internal dissipation in mag- 
netostriction transducers. In units employing 
radial or longitudinal vibration of nickel tubes, 
this effect is especially prominent and led to 
many schemes, some practical and some im- 
practical, for reducing the eddy currents by 
lamination. Proposals for the use of stacks of 
flat laminations by which the eddy currents 
could be minimized were also made and tests 
of experimental laminated stacks revealed the 
soundness of this conception. Quantitative 
analysis of the vibration of asymmetrical lam- 
inations made it possible to compute the effi- 
ciency of electroacoustical conversion and also 
to choose the configuration of the lamination 
in such a way as to provide a desirable sharp- 
ness of resonance for bandwidth coverage and 
to produce a useful degree of preferred radi- 
ation from the face of the stack in contact with 
the water. Similar analysis was extended to 
laminated stacks of thin rings which proved 
to offer a desirable range of acoustical per- 
formance characteristics. 


Types of Transducers 

The principal types of magnetostriction 
transducers made available by this research 
program may be classified as follows: 

Radially Vibrating Tubes. In one arrange- 
ment the driving coil and polarizing magnet 
are contained inside the magnetostrictive tube 
leading to a transducer which is convenient to 
mount and handle. Units of this type were em- 
ployed in the sound gear monitor for sonar 
testing. Several thousand units were procured 
by the Navy during World War II. 

Asymmetrical Laminated Stacks. Two forms 
of the asymmetrical laminated stack received 
wide usage. One of these provided a 60-kc trans- 
ducer having unusually good directional char- 
acteristics for use in echo-ranging types of 
homing ordnance. Another type of asymmetri- 
cal stack was used in the multielement cylin- 


MAGNETOSTRICTION TRANSDUCERS 


147 


drical transducers required in scanning sonar 
systems. 

Laminated Ring Stacks. The laminated ring 
stacks were usually provided with a toroidal 
winding and the entire unit encased in a molded 
plastic shell. Altering the diameter of the rings 
controlled the resonance frequency whereas 
the radial thickness of the lamination con- 
trolled the sharpness of resonance over a wide 
range. Transducers could be made in this way 
to have substantially uniform response over a 
wide frequency range. In this respect the ring 
stacks had a frequency response comparable 
with the tubular units (first type described) 
but operated at a considerably higher efficiency. 

Tube and Plate Transducers. This type of 
unit was employed in the sound projectors 
widely used in sonar equipment at the begin- 
ning of World War II. As a result of studies 
by HUSL and BTL, the efficiency of such units 
was markedly increased and design factors 
were elucidated so that the characteristics were 
controllable. One unit of this type received wide 
usage in underwater homing ordnance devices. 

Miscellaneous Forms. These included units 
employing flexural vibrations and some novel 
forms which revealed interesting possibilities 
for development not fully exploited by this 
program. 


Directivity Theory 

Almost every laboratory engaged in appli- 
cations of subsurface sound gave some atten- 
tion to analysis of the directional patterns of 
sound radiators. The primary objective of the 
studies was to provide a means for eliminating 
the spurious sound radiation characterized by 
minor lobes in the directivity pattern. Methods 
for control of the directivity patterns were 
found through variation of the spacing of uni- 
formly excited transducer elements, variation 
of the vibration amplitude of uniformly spaced 
transducer elements, and variation of config- 
uration of arrays of uniformly vibrating ele- 
ments. Specifications were established for pro- 
ducing directivity patterns of any degree of 
sharpness and freedom from minor lobes, pro- 
vided the surface of the radiator could be ex- 


cited according to any prescribed pattern of 
phase and amplitude. These mathematical con- 
ditions had a physical counterpart in the con- 
struction of transducers as arrays of small 
stacks of thin laminations whose individual 
excitation could be controlled in accordance 
with the theoretical requirements. One typical 
transducer constructed on this basis was desig- 
nated SPEP and exhibited an excellent direc- 
tivity pattern as well as the high efficiency char- 
acteristic of the laminated stack construction. 

Theoretical consideration was also given to 
the formation of sharply directive sound beams 
by multielement cylindrical arrays of trans- 
ducer elements. Proper specifications for the 
distribution of amplitude and phase among the 
elements of the array were found and rela- 
tions were established for the conditions under 
which the directive patterns so formed could 
be caused to rotate about the axis of the array 
without distortion by suitably modulating the 
amplitude and phase of the excitation of the 
individual elements. In order to solve the math- 
ematical problems involved in these analyses, 
several mathematical functions were tabulated 
over extended ranges and new results were 
obtained for the behavior of a radiating line 
element located in a pressure-release baffle. 
These results were utilized in the design and 
construction of magnetostriction transducers 
for use in scanning sonar systems. 


Pilot Plant Facilities 

One element of research work in magneto- 
striction transducer design which became ap- 
parent during the wartime research program 
is the fact that a sizable pilot plant must be 
provided to build the experimental models re- 
quired for test purposes. In some cases this 
need arises from the fact that units must be 
constructed at substantially full scale in order 
to duplicate the conditions of water loading, 
while in other cases a significant factor in the 
performance of the final model is represented 
by the incidental elements such as bonding ce- 
ments whose characteristics cannot be ade- 
quately represented in small-scale models. For 
transducers of the type encountered in these 


148 


TRANSDUCER RESEARCH AND CALIBRATION 


investigations such pilot plant facilities must 
include punch press equipment for handling 
nickel laminations, rolls for strip stock, anneal- 
ing, impregnating and baking ovens, and equip- 
ment for casting plastics. In addition the elec- 
trical measurement equipment for observing 
the performance of transducer models demands 
the highest order of experimental skill in order 
to obtain reproducible results. For these rea- 
sons, a program of research in magnetostric- 
tion is not to be entered into lightly or without 
adequate resources. It may be that this feature 
would merit special consideration in connection 
with Federal support of further fundamental 
research in this field. 


9 14 Remaining Problems 

In spite of the gratifying results of the Divi- 
sion 6 research program on magnetostriction 
transducers, a great deal of work remains to 
be done in this field. Like all research programs, 
this one uncovered many new problems for each 
one solved. A few of the possibilities for fur- 
ther development in this field may be men- 
tioned. Most of the transducer designs that 
have been studied relate to vibrating systems 
of a single degree of freedom. In electric trans- 
mission networks and in other electroacoustic 
problems, it has been possible to improve the 
performance of the system by introducing, in 
a helpful way, additional degrees of freedom. 
The additional parameters afforded by such 
systems make it possible to provide for extend- 
ing the frequency range of uniform response. 
Further study could profitably be devoted to 
such wide-range transducers. 

In the field of magnetostrictive materials 
there is still room for improvement of the fac- 
tors which increase the tightness of the cou- 
pling between the electrical and mechanical cir- 
cuits and for further reduction of the eddy 
current losses. In other applications of iron- 
nickel alloys, eddy current losses have been 
drastically reduced by using the material in a 
finely powdered form embedded in a suitable 
binder. It was only possible to try one experi- 
ment involving magnetostrictive materials in 
powdered form. This experiment gave negative 


results for unknown reasons but it would seem 
worth while to pursue the matter further. Ad- 
ditional progress in improving the magneto- 
strictive properties of available materials must 
wait for improved understanding of the funda- 
mental physics of the ferromagnetic alloys. 



Figure 1 . Partially assembled HP-35 magneto- 
striction transducer showing use of preassembled 
laminated-type elements and wiring. 

92 PIEZOELECTRIC TRANSDUCERS 

The very diversified uses to which sonar was 
put during World War II have required the 
development of wide varieties of transducers. 
Thus sonar devices have been made for listen- 
ing, where their function is to make possible 
the perception of noisemaking objects such as 
a ship's propellers or the enemy's sonar gear; 
for echo ranging, to detect the presence of 
submarines and other objects; for sounding, 
to measure the depth of the water; for mask- 


PIEZOELECTRIC TRANSDUCERS 


149 


ing, to interfere with the performance of the 
enemy’s sonar; for decoying, to make sounds 
and noises which will mislead the enemy. A 
transducer is needed in every such device to con- 
vert electrical impulses into sound waves. With 
sonar devices ranging from large permanent 
installations on ASW ships and submarines to 
small expendable countermeasure devices, it is 
clear that a considerable variety of transducer 
designs are needed. These designs are fre- 
quently circumscribed by factors other than 
electromechanical efficiency and call for much 
ingenuity in their conception. Such ingenuity 
naturally must rest on a strong body of funda- 
mental physical knowledge of the factors in- 
fluencing the performance of all components of 
a transducer. 

Although the word, transducer, by its Latin 
derivation may properly be used to describe any 
device which converts energy of one type into 
some other type, we shall here limit out atten- 
tion to the conversion from electrical to acous- 
tical energy and vice versa. The reasons for 
doing this relate to the great flexibility with 
which an immense variety of controlled signals 
may be made by electrical means, together with 
the analytical ability of electrical receiving cir- 
cuits. Every transducer must contain as an 
element of its structure one part, called the 
motor, which can convert electrical energy into 
acoustical (mechanical) energy and back again. 
This conversion has been accomplished in sev- 
eral ways: electrodynamically, as in the con- 
ventional radio loudspeaker; by the magneto- 
striction effect as described in the previous sec- 
tion ; and by the piezoelectric effect. 

921 Piezoelectric Materials 

It was toward the end of World War I that 
Professor Langevin in France suggested the 
use of piezoelectric crystals for the motors of 
receivers and generators of supersonic waves. 
This marked the first commercial application 
of piezoelectric materials and was followed 
shortly by the development of crystal frequency- 
control devices, crystal filters, etc. Most of the 
research in the period of peace was devoted to 
these latter and only a little to the Langevin 
oscillator. 


Piezoelectric materials are crystals which, 
when compressed in particular directions, ac- 
cumulate electrical charges on certain of their 
surfaces. When an electrical field is established 
across these latter, the crystal expands or con- 
tracts in certain directions. The most com- 
mon of these substances are quartz, Rochelle 
salt, and ammonium dihydrogen phosphate 
(NH 4 H l .P 0 4 ). The first occurs naturally in 
certain parts of the world while the last two 
may be grown synthetically. The properties of 
a crystal are different in different directions. 
Consequently, to describe them, one must refer 
to certain natural directions in the crystal, 
which are called axes. For the crystals just 
mentioned only three axes, called X, Y, and Z, 
are needed. 

Quartz Crystal 

Imagine a slab cut from a quartz crystal so 
that the X direction is perpendicular to two flat 
parallel faces. If electrodes, such as pieces of 
tin foil, are attached to these faces, we should 
find that positive and negative charges would 
accumulate on the electrodes when the crystal 
was compressed by a force in the X direction. 

Langevin made the first sonar transducer by 
cementing a mosaic of X-cut quartz crystals 
between two heavy steel plates which also acted 
as electrodes. On impressing an oscillatory volt- 
age to the plates, the alternate extension and 
contraction of the quartz caused them to move 
in unison. By choosing the frequency of the 
oscillatory voltage to be equal to the natural 
frequency of the mechanical vibration of the 
quartz-steel sandwich, the mechanical oscilla- 
tion could be made great enough to radiate an 
intense beam of sound when placed in water. 

Rochelle Salt Crystals 

Langevin’s sandwich became the prototype 
for the very successful ASDIC transducer de- 
veloped by the British Admiralty. A similar 
unit was developed for the U. S. Navy by the 
Naval Research Laboratory, but since the de- 
mand for quartz in the communication field 
was so great and since most quartz must be 
imported into the United States, an early effort 
was made to design American transducers 
around a more readily available material. The 


150 


TRANSDUCER RESEARCH AND CALIBRATION 


success of the Brush Development Company in 
growing large flawless crystals of Rochelle salt 
soon suggested the use of this material in place 
of the rarer quartz. 

Rochelle salt has a number of usable “cuts.” 
If a slab is cut from a crystal so that the faces 
to which electrodes are to be applied are per- 
pendicular to the X axis and the other edges 
are parallel to the Y and Z axes, we shall find 
that the application of an electric field in the 
X direction causes the slabs to distort so that 
one diagonal of the rectangular plate shortens 
while the other lengthens. This type of motion 
is of little use in sonar so the plate is cut at 
45 degrees to the Y and Z axes. In this case 
the motion will be either extension or contrac- 
tion. A similar piezoelectric bar may be cut 
perpendicular to the Y axis giving a 45-degree 
Y-cut unit. A cut which makes equal angles to 
all three axes is known as an L cut and has a 
thickness vibration characteristic similar to 
X-cut quartz though little use has been made 
of it so far. 

ADP Crystals 

Rochelle salt has many disadvantages. It con- 
tains water of crystallization which makes it 
difficult to handle and also seems to limit the 
amount of power which may be applied to it. 
At about 55 C it decomposes. In 1943, the Brush 
Development Company introduced a new piezo- 
electric crystal which came to be called ADP 
(ammonium dihydrogen phosphate). ADP is 
usable as a 45-degree Z-cut crystal. It has no 
water of crystallization, decomposes at 190 C, 
and is usable up to about 130 C. In very short 
time, this material was available in sufficient 
quantity to replace Rochelle salt, so that now, 
with a few exceptions, all new transducers are 
being designed around the better properties of 
ADP. 

By 1940 only a few actual crystal transducers 
had been developed. The best of these was the 
Navy’s JK listening hydrophone and its QB 
echo-ranging transducer. These were designed 
by NRL and the Submarine Signal Company. 
These units employed crystal arrays composed 
of 45-degree X-cut Rochelle salt. They were 
good transducers and served as examples of 
skillful design practice for some time. 


922 Need for NDRC Program 

When NDRC first began to work in the field 
of underwater sound it was not immediately 
realized that basic transducer engineering had 
yet to be established. A contract was entered 
into with BTL to design and build transducers 
for calibration uses. The Brush Development 
Company had also developed a series of useful 
calibration hydrophones. It was not until the 
principal central laboratories came to recog- 
nize that the commercial companies were not 
in a position to design transducers quickly to 
meet definite specifications that transducer re- 
search groups were built up. These groups 
learned that the closely related fields of piezo- 
electricity and elasticity had not been ade- 
quately developed, in an engineering sense, to 
meet the requirements of war. 

All the three central laboratories set up trans- 
ducer groups and apportioned work among 
them. Thus HUSL and CUDWR did much work 
with magnetostriction units but very little with 
piezoelectric units. UCDWR on the other hand 
dealt mainly with piezoelectric transducers. 
Operating principally under direct Navy con- 
tract, both the Brush Development Company 
and the Bell Telephone Laboratories [BTL] 
also did notable work and the OSRD labora- 
tories profited by the free exchange of informa- 
tion with them. 


92 3 UCDWR Program 

As an example of the type of research which 
was carried out in this field during World 
War II, the following description of the work 
done by the group at UCDWR is given. The 
transducer laboratory at UCDWR had its gene- 
sis in the need for transducers with which to 
carry on its work. At the beginning, several 
standard Navy units (magnetostriction) and a 
number of crystal units made by Brush were 
available, but it was soon realized that the 
limited performance inherent in these trans- 
ducers was seriously handicapping progress 
and the need for hydrophones and projectors 
with particular characteristics became more 
acute. 


PIEZOELECTRIC TRANSDUCERS 


151 


Because of the shortage of qualified personnel 
in the field of crystal physics and its offspring, 
transducer engineering, a cut-and-try method 
of design was used not only by UCDWR but by 
most other workers in this field. The practice 
at UCDWR was to design a transducer as well 
as experience and empirical data would permit 
and after making measurements on it, modify 
the design to bring its performance closer to 
that desired. This method of design is still 
being generally followed but design approxima- 
tions now come much closer to specifications. 

Analysis of Vibrating System 

A piezoelectric transducer is a very compli- 
cated vibrating system. A thorough realization 
of this is essential to the development of engi- 
neering practices. It had always tacitly been 
assumed that the crystal bars vibrated longi- 
tudinally with a frequency which depended 
only on the crystal length and the thickness 
of the backing plate to which the crystals are 
often cemented. This is only true when all di- 
mensions perpendicular to the vibrating dimen- 
sion are vanishingly small. This means that 
such a simple assumption would apply to a 
needle-like crystal attached to a needle-like 
backing plate. A single crystal of finite di- 
mensions will actually have many other modes 
of vibration in addition to this simple one and 
the coupling between such modes has great 
influence on the output of the crystal at differ- 
ent frequencies. One of the most useful prop- 
erties of crystals is the fact that they are not 
sharply resonant and a single crystal will radi- 
ate an appreciable amount of energy at fre- 
quencies far away from its resonance. However, 
when the frequency is close to the resonant 
frequency of some other mode of motion, this 
mode may be excited and the energy may not 
he radiated. In addition to coupling between 
many vibrational modes within the crystal it- 
self, there is similar coupling with the backing 
plate, the case, various cavities, etc. 

The multiplicity and complexity of these 
often make it seem as though a devilish intelli- 
gence were at work seeking malevolently to 
introduce irregularities in the performance of 
the transducer. Remedies for such irregulari- 
ties within the operating band are often tan- 


talizingly difficult to obtain, since the offending 
vibrational modes are often flexural and tor- 
sional. However, as one’s understanding of the 
ways in which such parasitic vibrations are 
stimulated grows, one’s ability to diagnose 
them and apply design remedies increases. 

This problem was attacked by UCDWR in 
two ways. A thorough study was made of the 
complex vibrations of a crystal and mathe- 
matical methods capable of dealing with them 
were developed. These studies have enhanced 
our understanding to a point where fairly ac- 
curate predictions of vibrational characteristics 
may be made. A further study was made ex- 
perimentally in a search for an answer to the 
question of why the directional patterns of 
transducers often failed to agree with theory. 
A small probe microphone with which one could 
explore the variation of velocity over the vi- 
brating face of a crystal array showed that 
such an array does not move back and forth 
like a piston but has great irregularities. These 
are particularly bad in the case where the crys- 
tals are cemented to a backing plate. Moreover, 
a single crystal is shown to vibrate in very 
complicated ways, depending on its dimensions 
and the amplitude of the driving force. Apply- 
ing this method to a backing plate or bar has 
led to a better understanding of the torsional 
and flexural vibrations of these driven com- 
ponents. A backing plate is simply a slab of 
some material, usually with parallel faces. To 
it are cemented the array of crystals so that 
the composite becomes the vibrating motor of 
the transducer. It is usually assumed that the 
backing plate stretches and contracts only in 
the vibrating direction. Actually it bends and 
twists and writhes as though possessed. These 
parasitic motions sap energy from the desired 
motion and thus impair the efficiency of a trans- 
ducer and spoil its beam pattern. 

Although these studies have served to expose 
many of the pitfalls which a design may ex- 
perience, they do not point uniquely to methods 
of avoiding them. In practice such “design ad- 
justment,” as it has been called, leading to com- 
plete or partial elimination of undesirable 
properties is still a matter of educated guess- 
work. The latter benefits greatly from experi- 
ence and a body of empirical knowledge. Fre- 


152 


TRANSDUCER RESEARCH AND CALIBRATION 


quently slotting the backing plate, breaking it 
up into a number of isolated sections, or alter- 
ing the location of the crystals on the plate will 
serve to change the frequency of parasitic oscil- 
lations so that they cease to be troublesome. 

The simple theory developed for slender crys- 
tals did not take account of frictional loads on 
faces other than the radiating ends. Thus an 
array of crystals is imagined as moving back 
and forth like a piston. In an actual transducer, 
since crystals are soluble in water, the motor 
is usually in a box filled with some liquid such 
as castor oil, which serves to transmit the 
sound to the sound window (usually rubber) 
and also to insulate the electrodes from each 
other. The motion of the crystals is such that 
the radiating ends must push the viscous castor 
oil aside while the sides slip through it. Both 
of these actions absorb energy and, since they 
contribute nothing to the radiated sound, tend 
to reduce the efficiency of the transducer. When 
the spaces between the crystal are too small, 
the energy absorbed in moving the oil in and 
out of such narrow crevices can be very large. 
Many of these matters are not obvious at first 
glance because of the minuteness of the motions 
which we are discussing. Actually the motion 
of a crystal in a transducer is not much greater 
than a wavelength of light and one’s failure 
to recognize many obscurities in transducer 
performance are traceable to this fact. 

Equivalent Circuits 

The timely publication of, “Electromechanical 
Transducers and Wave Filters,” by W. P. Mason 
of BTL in the spring of 1942 has been of in- 
estimable value to workers in this field. Mason 
developed and treated an equivalent circuit for 
a piezoelectric transducer which aids and sim- 
plifies the task of dealing with a practical de- 
sign. The idea of an equivalent circuit is old 
and useful in applied acoustics; this is partic- 
ularly so in the case of electromechanical trans- 
ducers where a mechanoacoustic circuit is con- 
nected to an electronic circuit. In practice the 
two influence each other, and in all treatments 
the circuit and the mechanical portion must be 
considered together. Use is here made of the 
formal mathematical similarity between the 
role played by masses, springs (compliances), 


and friction in mechanical systems to those 
played by inductances, capacities, and resist- 
ance in electrical circuits. Mason gave a circuit 
for piezoelectric crystal which is accurate for 
a long slender crystal, either free or on a simi- 
lar backing plate and which is loaded only on 
the ends. The load considered is normal and no 
account is taken of tangential or rubbing loads. 
The Mason circuit is one to which all more 
complicated circuits must reduce when applied 
to this particular case. It is, therefore, a check 
to be applied to other circuits. Dr. Glen Camp 
of the UCDWR group sought to extend this to 
practical transducers and evolved a circuit 
which successfully takes into account the finite 
size of actual crystals, loading on all crystal 
faces, tangential as well as normal, and the 
coupling between various modes of vibration 
in so far as they are practically important. 
As it must, Camp’s circuit includes Mason’s as 
a limiting case. 

Even though an equivalent circuit is of very 
considerable aid in simplifying design calcula- 
tions, it still involves long and tedious work. A 
small group of computers was set up at 
UCDWR to make such calculations. In addi- 
tion it has been possible in many cases, by 
suitable juggling, to devise equivalent circuits 
whose components are real. It is then possible 
to construct the circuit from resistances, con- 
densers, and inductances which may be found 
in the stock room. By making electrical meas- 
urements on such a circuit, one may quickly 
make design adjustments, simply by turning 
knobs. One has then a computing machine of 
great flexibility and convenience. This device, 
which has been called the LCR simulator, has 
proved its usefulness as a design aid. 


Construction Techniques 

Techniques used in the construction of trans- 
ducers have undergone considerable develop- 
ment. This was partially the result of the need 
for standardization in order that some control 
of quality could be exercised in production. The 
diversity of sizes and shapes of transducers also 
required great flexibility in assembly which in 
turn required variety in technique. Much work 


PIEZOELECTRIC TRANSDUCERS 


153 


has been done on cemented joints, on the type 
of cement, and the baking and conditioning 
procedure. An interesting case arose when it 
was noticed that ADP would tolerate the tem- 
peratures required to use the Chrysler Cycle- 
Weld process. It was thus possible to bond 
crystals to rubber so that either the rubber or 
the crystal ruptured before the bond failed. 
This technique permits one to attach crystals 
directly to the rubber sound window and elimi- 


Figure 2. The CJJ 78256 QLA transducer show- 
ing the crystal motor assembly. 

nates the need for the castor oil which usually 
permits the transfer of sound from the motor 
to the water. Such transducers obey theoretical 
predictions much better than those of conven- 
tional design. Methods have been found for 
strengthening the rubber windows so that such 
Cycle-Welded units give promise of being as 
rugged as those made otherwise. 

925 Contributions by Other Groups 

Much very excellent work has been done dur- 
ing World War II by other agencies in addition 
to OSRD. Most particularly, those responsible 
for the continued availability of crystals have 
contributed indispensably to the furtherance of 
transducer engineering. The Brush Develop- 
ment Company had, before World War II, de- 
signed and built a number of plants for grow- 


ing Rochelle salt crystals and had set aside a 
large stockpile of crystal bars. The patriotic 
and progressive attitude of A. L. Williams and 
W. R. Burwell of that company gave the coun- 
try the reserve of crystals needed for the heav- 
ily increased demands occasioned by war. Their 
continued support of fundamental research in 
crystal physics and physical chemistry led to 
the introduction in 1943 of ammonium dihydro- 
gen phosphate (ADP) by Dr. H. Jaffe and his 
associates. The realization of the usefulness of 
this new material led to a rapid development of 
growing methods so that before the end of 
World War II, plants at the Brush Development 
Company and BTL were in adequate produc- 
tion. A pilot plant for further study and con- 
trol of ADP was constructed and put into oper- 
ation by NRL. 

In addition to their work on transducers for 
calibration work, BTL entered into contract 
with the Navy for the development of improved 
sonar systems. During the course of this work 
they designed many excellent transducers and 
supplemented them with studies of a funda- 
mental nature. A BTL group did valuable work 
on crystals, cements, electrodes, oils, rubbers, 
and nearly every other phase of transducer 
engineering. The excellence of their work is 
nowhere better shown than in performance of 
their Navy projectors. 

The Sound Division of NRL under Dr. H. C. 
Hayes was very active both before and during 
World War II. Their attention was particularly 
focused on the design of new gear and on the 
basic study of crystal vibrations. NRL has dif- 
fered from UCDWR in the philosophy of this 
latter work, preferring the direct solution of 
the differential equations, with suitable bound- 
ary conditions, to the representation of the 
problem by an equivalent circuit. It is highly 
desirable that both methods be followed, the 
one to act as a check on the other. The direct 
method is somewhat more cumbersome to use 
but, when aided by the comprehensive charts 
recently published by W. J. Fry, J. M. Taylor, 
and B. W. Henvis (“The Design of Crystal Vi- 
brating Systems”) of NRL, can probably com- 
pete for accuracy and speed with calculations 
based on the equivalent circuit. They lack, how- 
ever, the convenience of the LCR simulator. 




154 


TRANSDUCER RESEARCH AND CALIBRATION 


9,26 Summary 

A number of related lessons have been 
learned from the concentration of work on 
piezoelectric transducers during World War II. 
The full appreciation of the position occupied 
by calibration stations in transducer engineer- 
ing has come somewhat slowly. Before World 
War II there was no centralized reference sta- 
tion. Everyone calibrated his own transducers. 
In 1942, Division 6, NDRC, established the 
Underwater Sound Reference Laboratories 
[USRL], described in Section 9.3. The USRL 
undertook the task of making frequent checks 
on the standard hydrophones and projectors 
used by all other activities, and there was fre- 
quent exchange of other transducers so that 
some idea was gained as to the reproducibility 
of the results of one station by another. This 
open and friendly self-criticism served to evalu- 
ate the state of the art of transducer calibra- 
tion. It is clear to all who have had much con- 
tact with transducers and their calibration that 
there is much room for improvement in this 
direction, and a very healthy step would seem 
to be the proposed establishment of the U. S. 
Navy Underwater Sound Reference Laboratory 
under the Office of Research and Inventions. 

A second lesson relates to the missionary 
work which transducer engineers have found it 
necessary to perform among their colleagues, 
the electronic engineers. A piezoelectric trans- 
ducer is a most unusual circuit element, by 
ordinary standards. The problem of matching a 
circuit to its transducer is complicated by the 
fact that it is not yet possible to design a trans- 
ducer with definite specifications. It is neces- 
sary that the specifications be established early 
in the development of a system and that the 
transducer engineer come as close as he can to 
meeting them. If, as often happens, some of the 
elements of the specifications are incompatible 
with others, it may be necessary to make com- 
pensations in the electronic circuit. Thus the 
systems engineer may ask for a certain beam 
pattern (fairly easy to predict), a certain im- 
pedance (less easy), a certain response over a 
wide frequency band (still less easy), and the 
whole thing to be within certain dimensions 
and weight (usually too small!). The trans- 


ducer engineer finds that he can, in a finite 
time, satisfy all the conditions except, say, the 
frequency response. The systems engineer will 
then try to equalize the output of his power 
amplifier to compensate for the slope of the fre- 
quency response of the transducer. Such hand- 
in-hand work has proved its value and an elec- 
tronics engineer who has been indoctrinated 
into the vagaries of the transducer can usually 
greatly assist the transducer engineer in pro- 
ducing the desired end result. 

The final lesson is derived from experience 
with the manufacture of transducers. Such ap- 
parently minor changes in technique materi- 
ally affect the performance of a unit, that sig- 
nificant differences are often found between 
laboratory-built and manufactured trans- 
ducers. It is important, then to assign a trans- 
ducer engineer to liaison work with a manufac- 
turer who is setting up to produce a particular 
unit and to follow this with periodic examina- 
tions of his product. 

Taking stock of the accomplishments of 
piezoelectric research and its offspring trans- 
ducer engineering, it is seen that the war pe- 
riod has led to a great improvement in the 
realization of the great complexity of the 
couplings between various modes of vibration, 
not only of the crystals themselves, but of the 
backing plates, cases, and all other components 
of the transducer. Improved methods of treat- 
ing the elastic problems mathematically have 
eliminated much of the guesswork from design. 
This elimination is not complete and the final 
stages of a design are still empirical. A better 
understanding of the nature and origin of para- 
sitic vibrations, together with a similar com- 
prehension of the factors contributing to en- 
ergy dissipation, have materially raised the 
overall efficiency of transducers. The accuracy 
of current calibration methods does not permit 
very good measurement of efficiency but in 
many specific models it apparently approaches 
a value of 100 per cent. Many small develop- 
ments in cements and other attachments to the 
crystals have improved construction methods 
and reduced variability between “identical” 
units. The transducer engineer may proceed 
more surely toward the design of a new and 
unique unit with greater promise that he will 


STANDARDS AND CALIBRATION MEASUREMENTS 


155 


succeed in meeting its specifications. A large 
measure of these improvements came at a suf- 
ficiently early date so that transducers which 
were used in combat were greatly improved 
over the prewar units. 


93 STANDARDS AND CALIBRATION 
MEASUREMENTS 

Whenever a surface vessel detects a sub- 
merged submarine and destroys it, whenever 
an acoustic mine functions properly, whenever 
an acoustic torpedo strikes its target, part of 
the success is due to a great mass of precise 
and detailed measurements of underwater 
sound. 

During an actual attack, these measurements 
are completely forgotten. This is quite proper. 
When a destroyer suddenly makes contact with 
an unidentified submerged target, the sonar 
officer rarely has time to consider the exact 
number of decibels emitted by his projector. 
But without these data, obtained many weeks 
or months or even years before, it is doubtful 
that his attack could be made and it is almost 
impossible that it could succeed. 

These measurements, carefully standardized 
and intelligently applied, have been found es- 
sential in almost every phase of sonar work 
from the very first stage of development 
through the training of operators and on to the 
time of actual attacks. They have been used ef- 
fectively during the research stage and during 
the development of preproduction models. Here 
experience has proved that significant progress 
is greatly accelerated when quantitative meas- 
uring techniques are available and when re- 
liable physical data, expressed in the terms and 
units standard for the art, can be obtained. 
They have been useful in full-scale production 
and in installation. They have been particularly 
valuable in testing and monitoring sonar equip- 
ment, in order to determine whether or not 
the gear is functioning properly. 

The groups of workers who coordinated their 
efforts in the field of sonar have found that 
these measurements, calibrated and presented 
in terms which are standard for all underwater 
sound studies, offered not only a yardstick but 


a language of comparison. Without this ma- 
terial, they found, it was difficult to use existing 
equipment at its maximum efficiency or to de- 
sign better equipment. 

At the outset of World War II, it was appar- 
ent that these measurements would be needed 
and that facilities, equipment, techniques, and 
men would be required to obtain them. In 1941, 
when NDRC undertook to cooperate with the 
Navy in underwater sound research and de- 
velopment, these requirements were promptly 
and carefully considered. In view of the urgent 
needs which were already evident, the rapidity 
with which subsurface warfare operations were 
expanding, and the probable directions of this 
expansion, an intensive program was clearly in- 
dicated. It was impossible then to forecast all 
the types of acoustical devices that would be 
needed in the constantly changing military 
situation, and accordingly the scope of the pro- 
gram was made as broad as possible. NDRC 
decided to make full use of peacetime develop- 
ments in acoustics and electronics, of the cur- 
rent practices in industry, and especially of the 
experience gained by U. S. and British Navy 
laboratories during the years between the two 
World Wars. 

The overall objective was obvious: Means 
and methods must be provided so that the scien- 
tists and the engineers could make quantita- 
tive measurements and make them with suffi- 
cient accuracy to fit the needs that were certain 
to arise. 

By the end of the war, not only had this 
broad objective been attained, but in addition, 
other significant goals had been reached. In- 
struments and techniques required for preci- 
sion measurements had been developed. Stand- 
ard terms, basic units, and reference points 
had been established and accepted so that the 
results of all quantitative measurements could 
be accurately and conveniently expressed. Ac- 
curacy had been improved to the stage at which 
sound in water could be measured at least as 
precisely as it heretofore could be measured in 
air. 

In short, it had become possible for the scien- 
tist and engineer to make quantitative studies 
of underwater sound phenomena, to measure 
the performance of underwater acoustical de- 


156 


TRANSDUCER RESEARCH AND CALIBRATION 


vices, and to express the results in terms that 
both could understand. Thus, in this field of re- 
search and development the mission had been 
accomplished. 

Major Objectives 

When NDRC began its work, the acoustic 
gear used by the Navy consisted principally of 
listening hydrophones and simple types of 
echo-ranging sonar. Even with this early equip- 
ment, there were no satisfactory devices or 
methods to measure their operation. No single 
type of underwater acoustical device was suffi- 
ciently reliable to serve either as a standard 
hydrophone or as a source of sound. In fact, in 
many instances, microphones or loudspeakers 
designed for air acoustics were hastily adapted 
to subsurface applications, applications for 
which they were wholly unsuited. To complicate 
this problem still further, radically new types of 
gear were rapidly developed by the Navy and 
NDRC and these required testing facilities 
which had hitherto been totally nonexistent. 

It was necessary, therefore, that an entirely 
new array of testing devices and techniques be 
developed and that they be placed in service so 
quickly that the development and testing of 
sonar equipment would not be delayed. 

Even though a rapid expansion in sonar had 
been expected, the speed of this expansion and 
the directions it followed were almost startling. 
At the close of World War II, acoustic systems 
of the greatest versatility and efficiency had 
been developed and put into use, and still others 
were under development. At each stage in the 
evolution of these devices, corresponding im- 
provements were urgently required in both the 
standardizing techniques and the instrumen- 
talities needed for precision measurements. 

The introduction of new enemy weapons 
made this problem even more acute. For ex- 
ample, the sudden appearance of the German 
acoustic torpedo made it imperative to develop 
and improve acoustical countermeasures. These 
countermeasures required improved methods 
for their measurement and evaluation, includ- 
ing the introduction and development of meth- 
ods for the accurate measurement of very short 
acoustical pulses. 


When it became apparent that newly de- 
signed German submarines were able to dive 
to very great depths in their escape tactics, 
changes were required in sonar detection gear. 
The resultant development of new depth de- 
termining sonars had to be paralleled and occa- 
sionally preceded by corresponding improve- 
ments and extensions in calibration methods 
suitable for their study. 

As a consequence of these and many other 
events, the operations of NDRC had to be as 
elastic as possible. In 1941, the initial require- 
ments for the program were written in terms 
of the equipment the Navy was using and de- 
veloping at that time. Laboratories were organ- 
ized, measuring equipment was designed, and 
investigations were laid out accordingly. But, 
as this equipment was changed or replaced by 
newer and different gear, the work of NDRC 
had to be modified. These modifications were so 
extensive and the need for them so great that 
it was necessary for NDRC’s measuring and 
standardizing facilities to be altered and en- 
larged continually. The development program 
for the testing equipment and improved stand- 
ards had to be planned so that the Underwater 
Sound Reference Laboratories would not 
merely be ready to work on new types of equip- 
ment soon after they had been developed but 
would actually be prepared in advance to make 
measurements on these radically new types as 
they appeared. Only in this way could NDRC 
meet Service needs and properly serve the war 
effort. 

Procedures 

Guided to a considerable extent by the ex- 
perience that had been built up by the Navy in 
underwater sound and by the work of universi- 
ties and industry in air acoustics, NDRC at- 
tempted to reach its various objectives by re- 
search and development work along both theo- 
retical and experimental lines. By keeping in 
constant touch with the Services and with in- 
dustrial laboratories which were developing 
new equipment, NDRC and its contractors were 
always able to anticipate well in advance the 
kind of precision measurements which they 
would be called upon to make on short notice. 


STANDARDS AND CALIBRATION MEASUREMENTS 


157 


The theoretical program was directed in part 
toward the definition and adoption of standard 
terms and units for expressing the results of 
underwater sound measurements. The terms 
and units were chosen with the aid of the Hy- 
drophone Advisory Committee appointed for 
this purpose by the Coordinator of Research 
and Development of the Navy. In formulating 
its recommendations, this committee made use 
of whatever definitions and terminology of air 
acoustics were applicable to subsurface sound. 
Particular attention was paid to terms and defi- 
nitions that had been adopted by the American 
Standards Association. In keeping with the 
general trend of terminology in air acoustics, 
units referring to a decibel scale were ex- 
pressed in terms of a pressure level rather than 
an energy level. The opinions of those actively 
engaged in this work during the war were 
ascertained before decisions were reached. The 
definitions and terms finally adopted by the 
committee have been recommended by the Navy 
for formal adoption by the American Standards 
Association. 

Theoretical work together with necessary ex- 
perimental investigation was also directed to- 
ward the specification of optimum testing 
depths and distances and toward a schedule of 
computation procedures so that the test data 
could be accurately and rapidly prepared in re- 
port form. 


Facilities 

The experimental work in this field was con- 
ducted largely by USRL, which operated dur- 
ing World War II on a contract between OSRD 
and CUDWR, and BTL, which operated on the 
basis of a contract negotiated between OSRD 
and the Western Electric Company. 

A great deal of valuable assistance was ob- 
tained from the Brush Development Company, 
the RCA Laboratories, the Submarine Signal 
Company, the Massachusetts Institute of Tech- 
nology Underwater Sound Laboratory, HUSL, 
and UCDWR. With the cooperation of these 
and other groups, work began immediately on 
the development of standard hydrophonic in- 
struments and measuring equipment and on 


the improvement of all experimental tech- 
niques. To a considerable extent NDRC looked 
to BTL to develop instrument standards and 
measuring equipment for the program. This 
work continued throughout World War II, with 
a continual evolution of instruments and meas- 
uring equipment and finally reached the de- 
velopment of instruments superior even to 
those previously used in air acoustics. As these 
improved devices were developed and accepted, 
every effort was made to obtain them in suffi- 
cient quantities for use by other NDRC facili- 
ties and by Navy ships and shore installations. 

It has been emphasized that this general pro- 
gram of precise measurement was constantly 
faced with changing and ever increasing re- 
quirements. To meet this challenge, it was 
found necessary to make available four com- 
plete calibration systems, two at Mountain 
Lakes, New Jersey and two at Orlando, Florida, 
each of which could cover the frequency range 
from 20 to 150,000 c. In addition, powerful am- 
plifiers able to deliver more than 1 kw of un- 
distorted power were provided for testing work 
at each station in order to handle the more 
powerful subsurface acoustic gear which soon 
appeared. 

Mountain Lakes Station 

At the Mountain Lakes station, three addi- 
tional test systems were provided for special 
work. One of these was a low-frequency system 
which operated over the range from 2 to 100 c 
and which was used to calibrate small hydro- 
phones for use in acoustic mines. These units 
were calibrated in a testing tank in which vari- 
ations of temperature and pressure could simu- 
late those which would be met in actual opera- 
tional use. The second was a large pressure 
tank and calibration system designed and con- 
structed for calibrations up to a water pressure 
of 300 psi on complete submarine sonar sys- 
tems. It made possible the evaluation of the 
acoustical performance of submarine sonars 
under operating conditions corresponding to 
deep submergence. The third was a high-fre- 
quency system for calibrations up to 2.2 me 
and was designed for use either in the open 
water of the lake or in a specially constructed 
acoustical tank. This high-frequency system 


158 


TRANSDUCER RESEARCH AND CALIBRATION 



Figure 3. Transducer mounting assembly and polar recorder used for making the transducer directivity 
response measurements. 


this system presents exceptional opportunities 
for further Navy investigations. 

The frequency range over which these vari- 
ous calibrations were made is in itself an indi- 
cation of how vastly the measurement program 
expanded. One of the first decisions made by the 
Navy and NDRC was the choice of this fre- 
quency range. In the beginning, it extended 
only from 100 to 50,000 c. At the close of World 
War II, it extended from 2 to 2,200,000 c. 

During this period, the powers of the sound 
sources and the sensitivities of the hydrophones 
were continually increased. In general, the 
guiding principle for the design of calibration 
instruments was that the acoustic power pro- 


studying the effect of temperature and pressure 
conditions and other pertinent physical factors 
actually encountered by sonar gear operating 
in the ocean. Thus, facilities were available for 
testing equipment at any temperature from 
arctic to tropical and at any pressure from that 
at the surface of the water to that at hundreds 
of feet below it. 

Perhaps the most important decision under- 
lying basic procedures at the various test sta- 
tions was the original one to conduct routine 
measurements in small fresh water lakes where 
freedom from tides, waves, and currents pre- 
vented interruption of regular work schedules 
and the low background noise minimized inter- 


was valuable not only in the calibration of small 
object locators operating in the megacycle fre- 
quency range but also in model studies on the 
echoes reflected from submarines. In this latter 
work, the wavelength of the sound was scaled 
down by a factor of 60/1 and the model of the 
submarine was built to the same reduced scale. 
It is felt that, for use in the study of models, 


jected into the water for test purposes should 
equal the power used in actual operations; in 
the same way, hydrophone sensitivities and ef- 
ficiencies should be increased to the point at 
which their effectiveness was limited only by 
the background noise encountered in their tac- 
tical use. 

Simultaneously, provisions were made for 




STANDARDS AND CALIBRATION MEASUREMENTS 


159 


ference with the most delicate calibrations. 
Once this decision had been reached and the 
frequency range selected for the tests, it was 
then relatively simple to set up the require- 
ments for the first standard hydrophones and 
procedures, the specifications for the auxiliary 
electrical and mechanical test equipment, and 
the techniques and routines for measurement 
and calculation. 


Results 

From all this work has come a wealth of in- 
formation and new equipment which not only 
had a significant effect on the outcome of World 
War II but also may confidently be expected to 
benefit science and industry in the future. 

The improvements in quantitative measuring 
and standardizing techniques, forwarded at 
once to all authorized organizations, made pos- 
sible the production and use of greatly im- 
proved sonar equipment. Production testing 
methods were applied in sonar factories and 
made possible the control of quality to an ex- 
tent never before realized on acoustical gear. 
With the newest and best techniques made 
available quickly to Navy groups, a high degree 
of accuracy was installed into practically all 
acoustical measurements made at sea and this 
was reflected in the increased efficiency of sonar 
equipment in combat. With the aid of CUDWR 
and USRL, acoustical measuring sets were sup- 
plied to measure and help in the control of noise 
produced by American submarines when oper- 
ating in combat areas. The acoustic monitor 
developed at HUSL made it possible to check 
the acoustic operation of the sonar on every 
destroyer while it was at sea. 

High on the list of the classes of acoustical 
gear which were calibrated and tested by 
USRL were echo-ranging and scanning sonars, 
shipboard and submarine listening systems, 
acoustic elements for the radio sono buoy, har- 
bor defense installations, acoustic torpedoes, 
acoustic decoys and other countermeasures, and 
instruments for quality control. The wide ap- 
plicability of this standardization work may 
be indicated by the fact that the measurement 
methods developed here were useful not only in 
developing these improved instruments, but 


were also suitable for important checks on their 
operation at sea. 

In addition to these purely military applica- 
tions, the work of the various NDRC groups 
may well find many important uses in industry 
and in the peacetime Navy. These include both 
instruments and techniques which have been 
made available for precision measurements. 

Many types of acoustical work will benefit by 
the use of such new piezoelectric crystals as 
ammonium dihydrogen phosphate [ADP], 
which were brought to the fore during wartime 
research. As a by-product in the development 
of better standard instruments, better methods 
were found for the utilization of the older 
piezoelectric materials such as quartz and Ro- 
chelle salts. 

Similarly, the increased efficiency of mag- 
netostriction devices and electromagnetic in- 
struments, which resulted from the full utili- 
zation of new materials and from fundamental 
improvements in the theory and practice of 
magnetic circuit design, will contribute to 
many lines of peacetime acoustical engineering 
and other related fields. 

Many other general applications will be 
found for acoustic gear with greater power- 
handling capacity, for equipment with wider 
frequency responses, and equipment which re- 
sponds with high fidelity when used with very 
short pulses and other special signals. 

Among the wide variety of new acoustical 
techniques perfected during World War II and 
available for future use may be cited the appli- 
cation of enclosed testing tanks in which side- 
wall reflections were eliminated by the use of 
short pulsing techniques, a method which was 
aided by parallel developments in the field of 
radar. Without such methods, a large number 
of calibration and factory production test pro- 
cedures would have been completely imprac- 
tical; with them, many future and apparently 
impossible goals may be achieved. 

Further advances in this field will be stimu- 
lated by the inevitable improvements in sonar 
equipment itself. As sonar gear is changed and 
developed along still uncharted courses, im- 
provements in precise measuring and standard- 
izing will be essential. Measurements must be 
still more precise and standardization tech- 


160 


TRANSDUCER RESEARCH AND CALIBRATION 


niques still more stringent. More complete lab- 
oratory facilities must be provided to include 
not only deeper fresh-water testing lakes, but 
also larger indoor tanks able to withstand 
higher pressures and to operate over wider 
temperature ranges. Continual improvements 
will be required in the standard hydrophonic 
instruments themselves and in the associated 


electrical equipment to provide higher testing 
powers, wider frequency ranges, and greater 
sensitivity. 

So long as the Navy develops and expands its 
use of underwater sound in subsurface opera- 
tions, the related field of measurement and 
standardization must develop and expand with 
it. 


Chapter 10 

TORPEDOES AND FLUID DYNAMICS 


W orld War II brought to those responsible 
for our naval preparedness the realization 
that the development of improved torpedoes was 
essential if we were to defeat the Nazi U-boats 
in the Atlantic and the Japanese Navy and mer- 
chant fleet in the Pacific. The task of providing 
fundamental design information leading to bet- 
ter and more efficient torpedoes was assigned 
by Division 6 to the Special Studies Group of 
Columbia University Division of War Research 
[CUDWR], 

The study of the travel of projectiles in fluid 
media, both in the water and air, and during 
the critical transition from an air to a water 
path had already been launched by a group at 
California Institute of Technology [CIT] con- 
cerned with the development of a fast-sinking 
depth charge. 

These two research programs, although inde- 
pendently administered, had considerable areas 
of mutual interest. The fluid dynamics research 
work soon became concerned with many types 
of projectiles including torpedoes, with special 
emphasis on the development of an aircraft tor- 
pedo which could be launched from high alti- 
tudes and at high speeds. And as the torpedo 
research work developed, the Special Studies 
Group was able to concentrate on the theo- 
retical phases, depending on the CIT group for 
proving and testing. 

101 TORPEDO RESEARCH 

World War I had stimulated the development 
and design of self-propelled, self-steered under- 
water torpedoes. Although research and devel- 
opment were continued after that war, no ex- 
tensive improvements had been made in the 
methods of torpedo launching, propulsion, 
steering, and charge-exploding. Torpedo de- 
velopment had not kept pace with the improve- 
ments in the defenses of naval and merchant 
vessels. At the beginning of World War II, it 
became apparent that a more effective and more 
efficient torpedo was required to fight surface 
and subsurface warfare. 


The overall problem of improving torpedoes 
was assigned to Division 6, but the most press- 
ing demand was for improvement in the per- 
formance of torpedoes launched from aircraft. 
Since little seemed to be known in a quantita- 
tive way about the stresses at water entry, and 
about the necessary characteristics of such tor- 
pedoes, it was decided to carry out fundamental 
research in parallel with the design and con- 
struction of experimental torpedoes. 

This work involved research in problems of 
torpedo air flight, water entry, and underwater 
travel. Research was also conducted on propul- 
sion systems and steering control. 


Propulsion 

When the division took up the problem of im- 
proving torpedo propulsion, there were three 
systems of power to be considered: (1) electric 
power from a primary or storage battery; (2) 
burning of fuel to drive a turbine or engine; 
(3) utilization of some form of jet propulsion. 

The division was not primarily responsible 
for any substantial research or development of 
jet propulsion, although it did to some degree 
advise and furnish test facilities to organiza- 
tions other than its contractors. Therefore, jet 
propulsion will not be discussed in this volume. 

In investigating the other two systems, theo- 
retical studies were combined with practical 
engineering skill to work out the best combina- 
tions. 

An analysis and assessment of electric and 
turbine propulsion showed that electric propul- 
sion offers certain advantages. An electrically 
driven torpedo leaves no wake of surface 
bubbles which might be detected during ap- 
proach by the target ship and offers a much re- 
duced maintenance problem. It was found that 
electric propulsion had previously been re- 
stricted to certain types of torpedoes because 
the battery weight limited the running time or 
range, and the problem was to develop an elec- 
tric system which would provide for longer 


161 


162 


TORPEDOES AND FLUID DYNAMICS 


running time or greater range by means of a 
lighter battery. 

The Bell Telephone Laboratories [BTL] 
worked on this problem and developed a 
primary sea-water battery, which provides a 
much longer range with a given battery weight. 
At the same time, the division designed a 
counterrotating motor and demonstrated its 
possibilities. This design not only reduced the 
weight necessary for providing the required 
power, but eliminated the troublesome system 
of gears necessary to drive the counterrotating 
propellers. With this advantage was combined 
the automatic balancing of the torques applied 
to the propellers and the consequent elimina- 
tion of the necessity for careful balancing of 
the propellers. An analysis of the properties of 
the sea-water battery and the counterrotating 
motor indicated that this combination promises 
to be a highly useful solution of the battery pro- 
pulsion problem. In addition to the advantages 
of ease of maintenance it provides an energy 
per unit weight equal to that of the best tur- 
bine-driven torpedoes in use during World War 
II. However, this system has not yet been tried 
operationally. 

The division also conducted substantial re- 
search in the problems of engine or turbine 
propulsion. An investigation of existing pro- 
pulsion mechanisms showed that this portion of 
a torpedo occupies the major part of the tor- 
pedo both in volume and in weight, and that 
the overall size of a torpedo is largely deter- 
mined by the requirements for speed and range. 
Therefore to achieve maximum speed and 
range, with a given weight, the power plant 
must be as light, compact, and efficient as pos- 
sible. Unlike a surface ship, a torpedo must 
carry not only its fuel, but also its oxidant. 
Therefore, the problem was to improve the 
efficiency of torpedo operation by designing a 
highly efficient engine that uses the lightest 
fuel and oxidant possible. 

Investigation of various oxidants, such as air 
and oxygen, showed that they are most efficient 
in the form of a liquid. A liquid oxidant re- 
duces the weight of the fuel and container by 
60 per cent merely by reason of being liquid 
rather than gaseous. The most highly developed 
system was found to be one which uses liquid 


hydrogen peroxide as an oxidant. The investi- 
gations showed that any further improvement 
in the weight of fuel and its container can be 
translated directly into increased torpedo 
range, increased running time, or increased ex- 
plosive charge, depending on the torpedo char- 
acteristics desired. 

An extensive study of propulsion mechan- 
isms was also made by the Navy Department 
and these data provide the basis for future tor- 
pedo propulsion development. 

101 - 2 Air Flight 

In order to improve the efficiency and effec- 
tiveness of aircraft-launched torpedoes, the di- 
vision undertook a program of research and 
theoretical study concerning the behavior of 
torpedoes in the air, at water entry, and dur- 
ing underwater travel. These studies indicated 
numerous necessary improvements in design. 

An investigation of aircraft torpedo tactics 
and the conditions under which an aircraft tor- 
pedo is launched indicated the desirable specifi- 
cations. When a torpedo is launched, it usually 
can be observed by the target, and the target 
may have time to take proper evasive action. 
A study was made of means to make evasive 
action difficult or ineffective and it was found 
that the most difficult way would be to try to 
increase the underwater speed. Since the speed 
of travel in air is so much greater than any 
possible underwater speed, it was concluded 
that most of the distance between the point of 
release and the target should be covered by air 
travel. Advantage could then be taken of the 
speed of the plane and the altitude from which 
the torpedo could be dropped. 

The problem, then, was to develop a weapon 
which could be launched from very high-speed 
planes, from high altitudes, equipped with a 
sufficient power plant to travel a short distance 
under water at moderate speed, and which 
would pursue the proper course at proper depth 
to reach its target. 

Theoretical study as well as experiments em- 
phasized that not only should the torpedo be 
rugged in construction to withstand the shock 
of water entry, but also that the torpedo must 
end its air travel in such a way as to make a 


TORPEDO RESEARCH 


163 


clean and smooth entry into the water. Experi- 
ments showed that a 15-ft horizontal drop of a 
torpedo might be more damaging than a clean 
entry from high altitude at speeds of over 200 
knots. Thus, it was found that serious damage 
to the torpedo could only be minimized by pro- 
viding for a clean water entry. 

Investigations of means of achieving clean 
water entry showed that the torpedo must be 
traveling parallel to its axis at the time of the 
impact with the water, but this could be accom- 
plished only by proper stabilization of the tor- 
pedo in the air. 

Before the division undertook this work, the 
Navy had started using air stabilizers that 
break off on water entry. Experiments were 
conducted with torpedoes using no control sur- 
faces and with torpedoes using various kinds of 
stabilizers. A simple cylindrical body tends to 
set itself perpendicular to its direction of 
travel. But when a large tail is added, this tend- 
ency is overcome and the torpedo then tends to 
travel parallel to its axis. The large tail is un- 
desirable during the underwater run, and to 
solve this problem a tail of light wood was con- 
structed, which breaks off on water entry. 

In addition to the tail, other stabilizers are 
required to overcome certain forces working 
on the torpedo during its air flight, which tend 
to prevent it from entering the water smoothly 
and cleanly. A wide variety of stabilizers were 
tried but the most satisfactory was found to be 
the Mark 2-1 stabilizer combined with a drag 
ring, or pickle barrel on the nose. The Mark 2-1 
stabilizer is a simple wooden box that is slipped 
over the torpedo fins and the drag ring is a 
short wooden cylinder that slips over the nose. 
According to the experiments, the combined 
effect of these two devices is to cause the tor- 
pedo to be stable when traveling parallel to its 
air trajectory. 

Investigations also proved that there are ini- 
tial disturbances caused by release conditions, 
which require some time to be damped out. 
Thus, it was indicated that by increasing the 
launching altitude, the time in which this 
damping action can be effected is also increased. 
Also, this damping effect increases with speed, 
so that a high-speed launching may tend to be 
cleaner than a low-speed launching. 


While working with stabilizing appendages it 
was found that they are effective only in caus- 
ing the torpedo axis to remain parallel to its 
trajectory with respect to air. If there is a 
wind, the trajectory with respect to air will 
not be identical with the trajectory as seen 
from the ground (or water) and it is the trajec- 
tory as seen from the ground that determines 
water-entry conditions. 

Analysis showed that a torpedo stabilized on 
its trajectory and traveling with a tail wind 
tends to enter the water nose-down, or travel- 
ing in a head wind, it tends to enter nose-up. A 
torpedo traveling in a crosswind will enter with 
a certain amount of yaw. Although the effects 
of wind cannot be overcome by simple air sta- 
bilizers, these effects cannot be neglected be- 
cause they affect the underwater behavior of 
the torpedo. The division recognized and re- 
corded these effects, so that proper allowance 
can be made for them in tactical methods. 


Water Entry > 

The water-entry phase of an aircraft tor- 
pedo was found to be less subject to theoretical 
analysis than either the air travel or under- 
water travel. When the division began to study 
the problem, almost no information was avail- 
able as to the torpedo’s behavior during this 
phase. Water-entry study is greatly compli- 
cated because of the vastly different properties 
of air and water, so that it was possible to es- 
tablish only a more or less phenomenological de- 
scription of torpedo behavior during this phase. 

Tests and studies were conducted to deter- 
mine the magnitude and duration of forces act- 
ing on the torpedo when it strikes the water 
and how these forces determine its underwater 
behavior . Calculations and tests were also made 
to determine how to control the water-impact 
phase by properly shaping the nose of the tor- 
pedo and to determine what effect, if any, cer- 
tain torpedo appendages have on the initial un- 
derwater trajectory. 

Although it was not possible to determine the 
exact magnitude or duration of the impact 
force, it was possible to calculate the total im- 
pulse associated with this force. Theoretical 


164 


TORPEDOES AND FLUID DYNAMICS 


analysis and tests showed that the impact force 
produces both a sudden change of longitudinal 
velocity and a sudden access to angular velocity 
about a horizontal axis. The change in longi- 
tudinal velocity apparently plays no signifi- 
cant part in determining subsequent behavior 
but the sudden access to angular velocity causes 
the nose to rise and the tail to fall, and deter- 
mines whether the subsequent trajectory turns 
upward or downward. 

It was found that after initial impact, the 
torpedo creates a cavity, roughly conical in 
shape, so that only the nose is in contact with 
the water. This continues until the torpedo is 
several lengths under the surface and during 
this time the torpedo is subject to a decelerat- 
ing force which tends to turn the torpedo more 
nose-down if the torpedo is nose down to its 
trajectory, and therefore tends to overcome the 
initially produced nose-up angular velocity. If 
the torpedo is nose up to its trajectory, the 
drag force adds to the initially produced up- 
ward angular velocity. Therefore, the torpedo 
tail will eventually strike either the top or the 
bottom of the cavity. If it strikes the top, the 
torpedo will travel in a roughly circular path 
concave-downward. If it strikes the bottom, it 
will travel in a path concave-upward. Which 
path is followed depends upon the magnitude 
of the initially acquired angular velocity and 
the later angular acceleration that either adds 
to or subtracts from the initially acquired 
angular velocity. This depends on the pitch and 
trajectory angles at entry. 

The forces producing the suddenly acquired 
angular velocity and the dependence of these 
forces on the entry conditions depend on the 
shape of the torpedo nose. Most nose shapes 
give the torpedo an upward impulse but suffi- 
ciently blunt noses give it a downward impulse. 
Blunt noses are rarely used on aircraft tor- 
pedoes because of the large drag associated 
with them, so the investigations dealt with 
finer shaped noses. Since the angular velocity 
acquired at impact depends on the nose shape, 
the critical pitch angle varies with the nose 
shape. 

According to the studies, the major features 
of the initial underwater trajectory are appar- 
ently determined before the cavity closes, so 


that these features are not influenced by move- 
ment of rudders or elevators and consequently 
are not dependent on the depth-control mechan- 
ism or the steering device. Of course, these 
mechanisms are important in determining tra- 
jectory after the cavity closes, when the nor- 
mal hydrodynamic forces begin to act. The 
hooks to the right or left, as well as the maxi- 
mum depth of dive, are influenced by the be- 
havior of the depth mechanism, the extent to 
which the elevators are reduced in effectiveness 
by a shroud ring, and the extent to which the 
torpedo heels over. 

Investigation and analytical studies showed 
that if the steady-state hydrodynamic con- 
stants of the torpedo are known, the trajectory 
after collapse may be roughly calculated. 

On the basis of such a study it was possible 
to predict with some degree of certainty the 
initial underwater behavior of the Mark 13 
torpedo. It was thought desirable to find some 
shape of torpedo less sensitive than that of the 
Mark 13 to pitch angle and yaw angle at entry, 
and analysis indicated that it is quite possible 
that a proper combination of nose shape and 
large tail structure may overcome this sensi- 
tivity. However, at the present time there is no 
convincing evidence that any shape is signifi- 
cantly better than that of the Mark 13 or Mark 
25 torpedo as a compromise between the re- 
quirements for water entry and those for un- 
derwater travel. If tail and nose appendages 
could be discarded after water entry, better 
characteristics could be secured. 


101,4 Underwater Run 

A torpedo is equipped with a steering and 
depth-control mechanism to enable it to travel 
on a prescribed course at a fixed depth. Since 
it may have to travel for a considerable dis- 
tance underwater, the steering performance is 
of importance in determining whether or not 
the torpedo hits the target. Depth-keeping per- 
formance is important because it is necessary 
to set the torpedo to strike a ship below the 
armor belt. For these reasons, it was necessary 
for the division to investigate and study the be- 
havior of a torpedo underwater, and to design 


TORPEDO RESEARCH 


165 


steering and depth-control mechanisms which 
would function effectively. 

The division’s studies led to a fairly satis- 
factory theory of torpedo control. It was found 
that the behavior of a torpedo is the result not 
only of the control mechanism, but also of the hy- 
drodynamic characteristics of the torpedo body. 
These two things can be modified more or less 
separately, and the theory shows that the nec- 
essary properties of the control mechanism can 
be fairly well specified when the hydrodynamic 
behavior of the torpedo is known. 

The division studied torpedo models in water 
and wind tunnels, and full-scale bodies in tow- 
ing tanks, in order to determine torpedo prop- 
erties. The result of these experiments and 
studies was the development of a theory of dy- 
namic and static stability. It was found that 
most torpedoes are statically unstable. That is, 
if water is pumped past a torpedo, or if a tor- 
pedo is towed by an attachment at its center of 
mass, it will not continue to travel with its axis 
parallel to the direction of motion. Instead, it 
will turn one way or another, and set itself at 
a considerable angle. Addition of tail fins and 
shroud ring tend to reduce the angle to which 
it turns. Although this type of static instability 
is striking, it is of relatively little significance 
to the running behavior of the torpedo. 

In studying torpedo behavior, it was possible 
to set up a criterion of dynamic stability. A 
body is dynamically stable, if, when it is dis- 
placed from its straight course, it takes up an- 
other relatively straight-line course in a direc- 
tion slightly different from the original. On the 
other hand, if a body is unstable dynamically, 
and is displaced slightly from its course, it will 
go into a circle and continue to turn with a defi- 
nite radius of curvature. 

A body that is dynamically stable can be 
steered but it imposes a very considerable load 
on the steering mechanism. A body that is dy- 
namically unstable can be steered with much 
less anticipation in the rudder correction. 

A body that is statically stable will need 
very little steering, but it will be very difficult 
to turn. Therefore, because of simple shapes of 
conventional torpedo bodies, it was possible to 
set up a scale of stability in terms of hydro- 
dynamic constants of the body. At one end of 


this scale is a region of dynamic instability, and 
at the other end is a region of static stability. 
Between these is a region of static instability 
but of dynamic stability, in which a steering 
device can turn the torpedo in a reasonable 
circle and also keep it on a straight course with- 
out too great limitations being imposed on the 
steering mechanism itself. To make careful hy- 
drodynamic studies of any torpedo body, it was 
found to be important to study its behavior in 
straight-line motion, in curved motion, without 
propellers, and with propellers— both driven 
and free. 


Steering Mechanisms 

On the basis of the hydrodynamic studies of 
torpedo behavior, it was possible to specify the 
necessary properties of a control mechanism. 
The division considered two types of control, 
two-position mechanisms and proportional 
mechanisms. 

A proportional mechanism works in such a 
way that the rudder displacement of the tor- 
pedo is proportional to the amount by which 
the torpedo axis departs from its prescribed 
direction. In a two-position mechanism, the 
rudder is thrown hard over to one side or the 
other as soon as the torpedo departs more than 
a prescribed amount from its proper direction. 
Other types, which may be described as inter- 
mediate, were also considered. 

Experiments showed that a proportional 
mechanism may result in unstable oscillations 
of increasing magnitude if it is applied to a 
torpedo without consideration of the hydro- 
dynamic properties. This happened when the 
control was too stiff. Such an unstable system 
is, of course, unsatisfactory because the torpedo 
wanders widely from side to side. Instability of 
this kind was corrected by reducing the amount 
of rudder throw, or by reducing the rudder 
area, but such a remedy reduced the curvature 
of the torpedo path, making it more difficult to 
turn the torpedo in a prescribed direction. It 
also slowed the correction of the course. It was 
found, therefore, that in designing a steering 
mechanism, proper balance must be struck be- 
tween the necessity for stability and the neces- 


166 


TORPEDOES AND FLUID DYNAMICS 


sity for a sensitive control, or for quick restora- 
tion after disturbance. 

Experiments showed that the two-position 
control always results in oscillation of the tor- 
pedo about its course. However, studies proved 
that if this oscillation can be made of high 
enough frequency and of low enough amplitude, 
it is not serious. Therefore, if a two-position 
control is properly designed and built, it will 
steer just as well as a proportional control al- 
though its specifications will be somewhat more 
severe than those of a proportional control. 


10,1,6 Depth-Control Mechanisms 

In assessing depth-control mechanisms, the 
division considered types that operate in the 
same two ways as the steering mechanism. A 
depth-control mechanism may produce an ele- 
vator deflection that is proportional to a given 
signal or combination of signals, or it may put 
the elevator either hard up or hard down. 

Experience proved that in order to get ade- 
quate depth-keeping, it is necessary to have 
some kind of an anticipatory device which will 
recognize any attempt to turn up or down and 
restore the body to proper level even before the 
body has changed its depth. 

Many kinds of anticipatory devices were sug- 
gested and considered, but the one given the 
most attention was the pendulum and it is the 
one in most common use. Experience indicates 
that this is also the simplest device. Neverthe- 
less, it was found that the pendulum has nu- 
merous disadvantages. It has a natural period 
of its own and it is important that this period 
does not come too near to the natural period of 
depth oscillation of the torpedo. Also the tor- 
pedo can oscillate at a certain frequency at 
which the pendulum will not indicate any oscil- 
lation at all. Study showed that these two dis- 
advantages can be taken care of to a large ex- 
tent in design and location of the pendulum, 
but only by imposing certain limitations upon 
the kind of pendulum that can be used. The 
most serious objection to the pendulum is its 
response to acceleration. When the torpedo is 
launched it accelerates, throwing the pendulum 
back, and hence the elevator down and when 


the torpedo hits the water, it decelerates, 
throwing the pendulum forward and hence, the 
elevator up. Despite these objections, however, 
no other mechanism was found which per- 
formed better, and it may well be that the 
pendulum, because of its simplicity, will always 
be the most satisfactory, and that its disad- 
vantages can be minimized by suitable design. 

Studies were also made to improve the pen- 
dulum depth-keeping system. Analyses of vari- 
ous proposed systems showed that a device sen- 
sitive to the time rate of change of depth can 
be constructed to assist in stable depth-keeping. 
If used with a pendulum, stability can be guar- 
anteed and the disadvantages of using a pendu- 
lum alone can be minimized. However, it re- 
mains to be determined whether the additional 
complication is justified. 

The gyroscope was also studied for use in in- 
dicating the vertical, but it was not given ex- 
tensive service trial. The principal result of the 
studies of depth-keeping was the development 
of a theory by which it is possible to predict 
the performance of any projected mechanism. 
A mechanism already constructed can be ex- 
amined in the laboratory but if the mechanism 
is only projected, its expected characteristics 
can be used to determine the behavior of a tor- 
pedo under its action. Tests showed that the 
theory gives a close and fairly detailed descrip- 
tion of torpedo behavior. Therefore, there is no 
longer any excuse for the laborious production 
of depth mechanisms that cannot be expected to 
operate at all. 


10,17 Sound Control Mechanism 

A major part of the division’s research and 
development program concerned the applica- 
tion of sound control to torpedoes and mines. 
Before sound control mechanisms could be de- 
veloped, it was necessary to study the behavior 
of sound in the sea and to combine this knowl- 
edge with the theoretical studies and research 
on torpedo behavior in its three phases of 
travel, and then adapt the sound control mech- 
anism to the hydrodynamic properties of the 
torpedo. 

Extensive research was carried out in the 


FLUID DYNAMICS 


167 


field of underwater sound. Experiments showed 
that maximum listening ranges are extremely 
variable, and may be affected by the speed of 
the torpedo, by the speed, size, and aspect of 
the target, by sea conditions, and by depth of 
water. 

Two basically different sound control sys- 
tems were investigated. In one system, the con- 
trolling sound source is the target itself ; hence, 
the designation of listening or acoustic con- 
trolled torpedoes. This system received the most 
attention and proved to be very effective. In 
the second sound control method, the torpedo 
itself projects a sound pulse in the supersonic 
range and is guided or directed to the target by 
the echo received from the target. This was 
designated as echo-ranging control. The first 
method was more fully developed. A sound con- 
trol device was needed that could be incor- 
porated in the existing body already being used. 
In order to get a working device in the shortest 
possible time, compromises had to be made to 
avoid discarding something already developed 
and taking the time necessary to go back and 
re-engineer parts of systems which were found 
unsatisfactory. Therefore, there is need for 
continuing research to improve the effective- 
ness of listening and echo-ranging control sys- 
tems. 


10 2 FLUID DYNAMICS 

The concern of Division 6 with the develop- 
ment of various types of projectiles dates back 
to 1941. The need for knowledge concerning 
specific projectile characteristics arose first in 
connection with the attempt of the division to 
develop more effective antisubmarine weapons. 
Thus the first projectile to be studied was the 
depth charge. As the needs of the division de- 
veloped, the list of projectiles grew until it in- 
cluded rockets of many types, bombs, shells, 
and torpedoes. In addition to the individual 
specific requirements, all of these projectiles 
were expected to have adequately accurate 
travel to the target and to utilize efficiently the 
applied propulsive force. As will be seen from 
the enumeration of projectile types, the method 
of propulsion varied over wide ranges, from 


simple fall under the action of gravity to con- 
tinuous propulsion by means of propellers or 
jets. Whether or not these requirements of ac- 
curacy and propulsive efficiency are met de- 
pends largely upon the interaction between the 
external forces resulting from the motion of 
the body through the surrounding air or water 
and the dynamic properties of the projectile 
itself, such as the mass, moment of inertia, 
and center of gravity. The external forces re- 
sulting from the motion of the projectile 
through the surrounding fluid are determined 
by the shape or form of the projectile, its orien- 
tation, and velocity. Early in the life of the di- 
vision, a brief investigation showed that com- 
paratively few reliable data were available con- 
cerning the fluid dynamic forces acting on a 
projectile of a given shape. Therefore, labora- 
tory research was indicated to obtain such in- 
formation to guide the design engineer. 

It should be understood that the forces act- 
ing on projectiles in flight represent only one 
very small subdivision in the field of fluid dy- 
namics. Many other structures employed in 
warfare fall within the same field. For ex- 
ample, submarines, surface ships, and air- 
planes all have to be designed primarily on 
the basis of the fluid dynamic forces that act 
upon them. Consequently, during the war years, 
an enormous volume of research and develop- 
ment has been carried out in this field. Progress 
reported here concerns merely this small seg- 
ment of the field and in itself is but a portion of 
the total research that was carried on in the 
fluid dynamics of projectiles. In this restricted 
segment, however, the division has sponsored 
the development of certain new laboratory 
methods for determining the dynamic forces 
acting on projectiles in flight and the utiliza- 
tion of these methods to obtain data that could 
be used in the design of new projectiles and in 
the modification of existing ones. 

It may have been noted that in this discussion 
the term fluid dynamics is used rather than 
aerodynamics or hydrodynamics. The reason 
for this has its origin in the projectiles with 
which Division 6 has been concerned. To reach 
the target, many of these projectiles have the 
first part of their travel path in air and the sec- 
ond part in water. To insure acceptable per- 


168 


TORPEDOES AND FLUID DYNAMICS 


formance, such projectiles must travel stably 
through each of these very dissimilar fluids. Of 
course, some of the projectile types, such as 
submarine torpedoes, have their entire travel 
wholly under water. On the other hand, certain 
of the rockets were designed for surface attack, 
and hence, their path involved air travel only. 
Thus, the relative amount of effort which had 
to be devoted to securing correct air travel and 
correct water travel varied with the specific 
projectile. It was soon found that to regard the 
travel of a projectile having a combined path 
as being simply divided between a period of air 
travel and a period of water travel unduly sim- 
plified the problem. Very frequently, in such 
cases, the transition period of water entry is of 
major importance. During this period there are 
obvious possibilities of mechanical damage to 
the projectile. Moreover, completely apart from 
the risk of damage, the fluid forces applied to 
the projectile during the entry period may also 
cause it to emerge from the water, to change 
direction sharply, or to get out of control and 
assume an erratic path in its subsequent under- 
water travel. As these facts were realized, they 
clearly demonstrated the need for special 
studies of the dynamics of water entry. 


10,2 1 Development of the Laboratory 

The first studies of projectile dynamics un- 
dertaken by the division were carried on by 
CUDWR for the purpose of supplying informa- 
tion concerning the design of certain depth 
charge ordnance. This work, while rather lim- 
ited in scope, produced valuable results which 
clearly indicated the desirability of providing 
more adequate facilities and plans for research 
and testing in this field. To provide a portion of 
these needed facilities, a contract was entered 
into in 1941 with the California Institute of 
Technology, which provided for the extension 
of the facilities of the Hydrodynamics Labora- 
tory of that institute and for the initiation of a 
program of research on projectile dynamics. 
The first research equipment constructed un- 
der this contract became known as the high 
speed water tunnel. The available equipment in 
the Hydraulic Machinery Laboratory served as 


a nucleus for this new construction. By making 
the fullest possible use of the existing instru- 
ments and equipment, the laboratory was en- 
abled to complete the water tunnel and start 
taking measurements within 4 months of the 
signing of the contract. The polarized light 
flume used for visual study of the flow patterns 
around projectiles was developed at the same 
time as an accessory to the main tunnel. At a 
considerably later date the design and construc- 
tion of a controlled atmosphere launching tank 
and a free surface water tunnel were under- 
taken. 

From the foregoing description of the ap- 
paratus constructed, it will be noted that the 
fluid medium chosen for the experimental meas- 
urements of the dynamic forces on the projec- 
tiles was water. There were several reasons 
for this choice. In the first place, at the time of 
the initiation of this work, the projectiles under 
consideration were largely those having only 
underwater paths. In the second place, the phe- 
nomenon of cavitation was frequently involved 
in the underwater behavior of projectiles, and 
since cavitation is a phenomenon that is pe- 
culiar to motion in a liquid, there is no very 
satisfactory way of studying it in a wind tun- 
nel. In the third place, the equipment available 
as a nucleus for the work was adaptable to use 
with water and not with air. Finally, it can be 
shown that over a wide range of conditions, 
the results obtained by study of a projectile in 
a water tunnel are almost equally applicable to 
the projectile in air travel. The only serious 
limitation is that when the results are applied 
to air travel, they must be restricted to cases in 
which the projectile velocities are sufficiently 
low so that the air can be treated as an in- 
compressible fluid. This means, in general, that 
the results obtained in the water tunnel can be 
applied with acceptable accuracy to the air 
flight of projectiles having velocities of less 
than 700 fps. 


Experimental Facilities 

High Speed Water Tunnel 

The high speed water tunnel is a vertical, 
closed circuit tunnel in which water is circu- 


FLUID DYNAMICS 


169 


lated continuously by means of a propeller 
pump driven by a variable speed motor. The 
working section, which is 14 in. in diameter 
and 6 ft long, is located in the upper horizontal 
run of the circuit. It has the smallest cross sec- 



Figure 1 . Group of stainless steel components 
for 2-inch diameter models. 


tion and consequently, the highest velocity and 
the lowest pressure in the circuit. The flow of 
velocity in this section can be maintained at 
any desired value up to 70 fps. The models of 


components for the 2-in. diameter models. This 
group illustrates the type of model construction 
developed by the laboratory. Measurements of 
the drag force, the cross force, and the moment 
can be made with a projectile aligned parallel 
to the direction of flow, or rotated in the hori- 
zontal plane to any desired yaw angle between 
plus and minus 20 degrees. The absolute pres- 
sure in the working section can be controlled 
independent of the velocity and can be held 
at any desired value from five atmospheres 
down to the vapor pressure of the water. The 
working section is provided with large Lucite 
windows for visual and photographic observa- 
tion purposes. Cameras with synchronized flash 
lamps of the Edgerton high-speed type are a 
regular part of the equipment. Although the 
propeller pump and drive motor produce con- 
siderable noise in the audible range, it has 
been found that the tunnel is comparatively 
quiet in the sound range above 6,000 c. There- 



Figure 2. The polarized light flume. 


the projectiles or other devices to be tested are 
mounted on the spindle of a three-component 
balance of the National Physical Laboratory 
type. Figure 1 shows a group of stainless steel 


fore, microphones mounted at the focal points 
of spherical and ellipsoidal reflectors have been 
developed for investigating the sound produced 
by the flow in passing the projectile, both under 




170 


TORPEDOES AND FLUID DYNAMICS 


cavitating and noncavitating conditions. These 
reflectors have double walls enclosing an air 
space and are installed in a water-filled tank 
attached to one of the Lucite windows directly 
opposite the model under test. Sound measure- 
ments with this equipment were made in the 
range of from 10,000 to 100,000 c. In order to 
study the effect of the propeller drive on pro- 
jectiles, small electric motors were developed 
that could be mounted within the model. These 
motors proved to be capable of driving the pro- 


make the flow lines visible, a suspension of 
M. S. Eyrite was employed as a circulating 
medium in place of clear water. This material, 
a species of Bentonite, has strong properties 
of streaming double refraction. When the flow 
is observed with transmitted polarized light, 
the shear pattern, and by analogy, the velocity 
pattern, become visible. Although the results 
from this flume are purely qualitative, they 
have proved to be very useful not only in de- 
lineating the general flow patterns, but also in 



Figure 3. Free surface water tunnel. Hydrodynamics Laboratory, California Institute of Technology. 


Pellers at correct model speeds and thrusts. 
The actual operating speeds of the propellers 
were as high as 18,000 rpm. 

Polarized Light Flume 

This piece of equipment was constructed to 
make possible visual studies of the flow pat- 
terns around various types of projectiles. The 
polarized light flume shown in Figure 2 is es- 
sentially similar to the high speed water tunnel 
in principle, but it is constructed on a much 
smaller scale. It has a working section 6 in. 
wide, 12 in. deep, and 4 ft long, and operates 
only at low velocities, the maximum being in 
the neighborhood of 5 or 6 fps. In order to 


locating various sources of disturbance which 
might cause an increase in resistance or loss 
in stability. The concentration of the suspended 
material is only a few tenths of 1 per cent, 
which has practically no effect on the other 
physical properties of the water. 

Controlled Atmosphere Launching Tank 

A more ambitious structure is the controlled 
atmosphere launching tank, which, with its 
associated apparatus, was constructed for the 
specific purpose of studying the water-entry 
problem. As the name implies, it differs from 
most launching tanks in that provision is made 
for control of the atmospheric pressure above 


FLUID DYNAMICS 


171 


the water surface. This control is necessary 
when working with scale models of projectiles, 
because the phenomenon of water entry is es- 
sentially one that involves the interaction be- 
tween the air and the water. Hence, in the 
model study, to simulate conditions which exist 
when full-sized projectiles are launched from 
the air into the ocean, it is necessary to reduce 
the air pressure in the same ratio as the linear 
scale of the model projectile. This tank, with its 
accessory equipment, was completed only a 




Figure 4. Interference of exhaust gases with 
propellers, stabilizing and control surfaces. 

short time before research under the Office of 
Scientific Research and Development contract 
terminated. 

Free Surface Water Tunnel 

During the course of the fluid dynamics re- 
search project, several problems arose in con- 
nection with the underwater travel of pro- 
jectiles which could not be investigated satis- 
factorily in the high speed water tunnel or 
other equipment available in the laboratory. 
One of these concerned the study of the be- 
havior of projectiles such as torpedoes, when 
they are traveling so close to the surface that 
the flow of the surrounding water loses its sym- 
metry. Another such problem involved the ef- 
fects of underwater jet propulsion, a study of 
which necessitates the introduction of compara- 
tively large quantities of gas into the flowing 
water in the test section. The free surface 
water tunnel was designed so that these and 
similar important sets of conditions might be 
studied. Although quite similar to the high 
speed water tunnel, it has a larger working 
cross section (20 in. square as compared to 
14 in. in diameter). The upper surface of the 
stream is in contact with the air. The air pres- 
sure is controlled for the same reason that was 
discussed in the preceding paragraph. Figure 3 


shows a sketch of this equipment as it will ap- 
pear when completed. It was still in the course 
of construction at the termination of the OSRD 
contract. 


Laboratory Program 

As has been seen, the laboratory program 
was developed primarily to meet the needs of 
the war research program. The main objective 
was to assist in the development of specific 
projectiles. From time to time, however, the 
accumulated data have been studied and eval- 
uated with a view to formulating more general 
conclusions. The reports of the laboratory, 
therefore, can be divided into these two classes : 
first, the presentation of characteristics of spe- 
cific projectiles and second, general conclusions 
concerning some phases of the projectile prob- 
lem. 

Specific Investigations 

In carrying out the investigations of the 
characteristics of specific projectiles, the high 
speed water tunnel has been used in the same 
manner as wind tunnels are used for testing 
airplane models. This means that accurately 
made scale models of the projectiles were con- 
structed and tested in the water tunnel to fur- 
nish information that could further the design 
and development of the projectile. Nearly all 
of these tests included the measurement of the 
drag, i.e., the resistance to forward motion; 
the cross force normal to the direction of mo- 
tion, and the turning moment about an axis 
passing through the center of gravity. These 
quantities were measured for a series of angles 
of yaw of the projectile axis with respect to 
the line of motion. The drag forces are useful 
in calculating the range and trajectory of the 
projectile and the amount of propulsion re- 
quired to maintain a constant velocity. The 
cross force gives an indication of the deviations 
from the normal trajectory which may be ex- 
pected, and the moment about the center of 
gravity gives one measure of the stability. 
Many other special types of measurements were 
made to suit the needs of the individual proj- 
ects. 


172 


TORPEDOES AND FLUID DYNAMICS 


Torpedoes 

A large part of the work of the laboratory 
was concerned with the hydrodynamic behavior 
of torpedoes. In addition to the normal meas- 
urements previously described, many determi- 
nations were made of the pressure distribution 
over the entire body of the torpedo. The re- 
sultant data were useful in evaluating various 
specific characteristics such as the operation of 
the depth-control mechanism and arming de- 
vices. Extensive tests were made on the speed 
and submergence at which cavitation would 
develop on various portions of the body, and 
on the effect of cavitation on the drag of the 
torpedo, the control characteristics, and the 
production of noise. 

In the case of the aircraft torpedo, studies 
were extended to include the characteristics 
during water entry. One outcome of these in- 
vestigations was the proposal by the laboratory 
that a shroud ring be added to the tail struc- 
ture. This modification was thoroughly tested 
under operating conditions by other NDRC 
groups and later by the Navy, and it was later 
adopted and used successfully. Another special 
study connected with the aircraft torpedo in- 
vestigated the effects of the exhaust pipe loca- 
tion on the interference by the exhaust gases 
with the operation of the propellers and the 
stabilizing and control surfaces. Figure 4 is a 
view of one such test. 

Bombs and Depth Charges 

Depth charges, like aircraft torpedoes, have 
both air and water flights. Several different 
designs of this type of projectile were studied 
chiefly to determine their drag and stability, 
with a view to improving their accuracy and 
increasing their fall velocity. Such studies were 
also made on a group of aircraft bombs which 
have quite similar characteristics, although 
they were designed for air flight only. 

Rockets 

Although this laboratory had no direct con- 
nection with the development of rockets, it 
carried out a rather extensive program of tests 
on rocket characteristics. This was due to the 
fact that many of the troubles encountered in 
rocket behavior developed during the burning 


of the propellent charge. It was found that 
water tunnel measurements of the forces act- 
ing on the rocket body could be correlated with 
the behavior of the rocket during this initial 
period and could be used to develop shapes that 
would have the desired performance character- 
istics. The rockets, for which model studies 
were made, ranged in size from the Bazooka 
projectile to the “Tiny Tim” aircraft rocket 
with a diameter of nearly 12 inches. 

Some cavitation studies were made in con- 
junction with these rockets since some of them 
were designed for use against underwater tar- 
gets. Though most of the rockets studied were 
of the fin-stabilized type, it was found that the 
water tunnel measurements were also of use in 
the design of spin-stabilized rockets. As a re- 
sult, the properties of several types of spinner- 
rocket projectiles were investigated in the 
tunnel. 


General Investigations 

Projectile Components 

Though the hydrodynamic characteristics of 
a given body shape cannot be predicted accu- 
rately from a knowledge of the properties of 
the component parts, this does not mean that 
a knowledge of the characteristics of the com- 
ponents is of no use. On the contrary, a com- 
pilation of such knowledge is of great value 
to the designer in guiding him in his work. 
Therefore, whenever possible, the laboratory 
has attempted to systematize the information 
it has collected on the various projectiles stud- 
ied. For example, an extensive series of dia- 
grams of the flow around noses, afterbodies, 
and tail structures of widely varying projectile 
shapes was published. In a few cases in which 
the results seemed to warrant it, the laboratory 
has gone a step further and made additional 
tests to obtain semiquantitative correlations. 
An example of this is the study conducted on 
the general characteristics of ring tails and fins 
as stabilizing surfaces for one given class of 
rocket projectiles. 

Cavitation 

More work of general significance was done 


FLUID DYNAMICS 


173 


K = 0.79 

SOUND = UNSTEADY 
NOISE LEVEL DUE 
TO INTERMITTENT 
CAVITATION 


B 

K * 0.77 

SOUND = 137 DB 


C 

K = 0.73 

SOUND = 139 DB 


D 


K - 0.68 

SOUND =138 DB 


E 


K = 0.65 

SOUND =135 DB 


F 


K = 0.60 

SOUND =130 DB 


G 


K = 0.56 

SOUND =129 DB 


H 


K = 0.50 

SOUND =128 DB 




K = 0.45 

SOUND = 125 DB 


K = 0.4 1 

SOUND = 123 DB 


K = 0.31 

SOUND = 115 DB 



■ ■ . . ■ i i i 1 1 i 1 

29 28 27 26 25 24 23 22 21 20 19 18 

DISTANCE ALONG AXIS. INCHES 


29 28 27 26 25 24 23 22 tl 20 19 18 

DISTANCE ALONG AXIS, INCHES 


Figure 5. Cavitation on hemisphere nose. 



DECIBELS ABOVE 0.0002 DYNES/ SQ CM 


174 


TORPEDOES AND FLUID DYNAMICS 


on various aspects of the cavitation phenome- 
non than on any other phase of the laboratory’s 
work. The reason for this is that, basically, 
cavitation effects constitute some of the most 
serious limitations to the satisfactory perform- 
ance of underwater bodies such as projectiles. 
Furthermore, less is known about cavitation 
than about most other hydrodynamic phenom- 
ena. The first general study in this field made 
by the laboratory concerned the production of 
supersonic noise by cavitation and the move- 
ment of the sound source and the variations in 
intensity that accompany the development of 
cavitation from the incipient stages to a bubble 
that envelops the entire projectile. Figure 5 
illustrates this development. Later, an exten- 
sive study was made on the effect of nose shape 
on resistance to the development of cavitation, 
with special emphasis on families of ogives, 
sphereogives, and ellipsoids. Studies were also 
started to determine the effects of various de- 
grees of cavitation on the drag resistance and 
the control and stability characteristics of pro- 
jectile shapes. 

Torpedo Control Characteristics 

During the life of the project a good many 
different torpedo shapes were studied. Al- 
though they had widely differing dimensions, 


they had many characteristics in common. 
Therefore, an attempt was made to integrate 
these results in a general analysis of the effect 
of body shape and the size, shape, and location 
of control surfaces on damping and dynamic 
stability of torpedoes. 

Aspects of the Program 

None of these general studies can be con- 
sidered as complete ; in fact, they are only 
started. It is felt that they can be pursued much 
further with considerable profit. Although the 
research program that has been described was 
wholly directed to the war effort, it has re- 
sulted in the development of equipment and 
techniques of measurement which can be most 
usefully employed in further research in mili- 
tary and civilian fields. Furthermore, many of 
the civilian and military needs for knowledge 
are complementary and can be pursued together 
to mutual advantage. A good example of this 
can be seen in the field of cavitation research. 
Here, practically all of the results are equally 
applicable to the movement of underwater 
bodies, such as projectiles and submarines, to 
the operation of ship and torpedo propellers, 
and to the behavior of general hydraulic ma- 
chinery, such as centrifugal pumps and tur- 
bines for hydroelectric development. 


PART IV 


EQUIPMENT DEVELOPMENT 




Chapter 11 


ANTISUBMARINE DETECTION EQUIPMENT 

By John S. Coleman 


111 INTRODUCTION 

W hen the problem of devising improved 
weapons to detect, locate, and sink enemy 
submarines was imposed on the United States, 
it was decided to concentrate immediately upon 
the large-scale production of equipment already 
designed and proved, rather than undertake 
major redesigns in an attempt to secure im- 
proved performance. 

This decision was not unjustified. For al- 
though the German submarine of World War II 
was a far more sophisticated and dangerous 
weapon than its World War I progenitor, great 
improvements had also been made in detection 
equipment, especially in echo-ranging gear 
which could accurately locate a submerged tar- 
get by measuring the transit time and direction 
of a reflected pulse of high-intensity sound 
energy. Radar, which uses radio pulses in air 
in the same manner, was rapidly becoming 
available for use on both surface and aircraft. 
However, as radar frequencies cannot pen- 
etrate more than a few inches of water, no 
equipment was available to permit aircraft to 
maintain contact with, or track submarines 
after submergence. 

In the field of antisubmarine ordnance, the 
picture was darker. With higher submerged 
speeds and greater submergence depths, the 
improved German submarines were much more 
difficult targets to hit with slow-sinking “ash- 
can” depth charges. Also, the improved hull 
design of the U-boat greatly reduced the lethal 
range of depth charges. Improved ordnance, 
having greater underwater velocity or the abil- 
ity to direct itself toward a target, was needed. 

On the other hand, our own submarines were 
not provided with entirely satisfactory gear. 
Like U. S. surface craft, they were equipped 
with hull-mounted echo-ranging gear. Subma- 
rine requirements, however, differ from those 
of surface craft. Since they must operate unde- 
tected by the enemy for maximum effective- 
ness, they prefer to use listening gear when- 


ever possible, rather than chance being detected 
by using their echo-ranging gear. Although the 
function of listening was available, it was pos- 
sible only in the supersonic range. Further, the 
location of the gear was not always convenient. 
One of the most serious deficiencies was the 
lack of instrumental aids and equipment for 
use during the depth-bomb attack and evasion 
periods, which could locate and anticipate at- 
tacks or serve as decoys or countermeasures 
for enemy detection equipment. 

With this picture in mind, the NDRC group 
attempted to plan a balanced and integrated 
program of equipment development to meet, 
at least in part, the many urgent problems 
presented. As trained and experienced person- 
nel were available only in very limited numbers, 
and time was all-important, it was decided to 
concentrate upon improvements to existing 
equipment which could be quickly manufac- 
tured and, if necessary, attached in combat 
areas as accessories, without delaying other 
parts of the Navy program. 

Such improvements were largely designed to 
close the gap between the performances of 
experienced and green, newly recruited oper- 
ators. Later, as experience and knowledge were 
acquired and the benefits of fundamental re- 
search became available, several long-term de- 
velopments providing improvements of a more 
fundamental nature were instituted. 

Five years is often given as the period nec- 
essary for new equipment to evolve from its 
laboratory experimental form to a production- 
type equipment. In the case of certain special- 
ized types of Navy equipment, which must sat- 
isfy extraordinary performance specifications, 
the period may be even longer. To assist its 
own research and development program, the 
division was forced to call upon many research 
scientists and their graduate students, most of 
whom were almost as unfamiliar with commer- 
cial engineering practices as they were with 
the highly specialized background of naval war- 
fare and operational doctrine. Experienced 


177 


178 


ANTISUBMARINE DETECTION EQUIPMENT 


manufacturers were swamped with new pro- 
duction difficulties and generally were not able 
to spare trained personnel. 

This situation, though it posed problems, 
worked out to the advantage of the program 
in several respects. New ideas and methods, 
borrowed from many specialized fields of re- 
search, were assimilated. Fresh concepts of the 
problems were derived, and analyzed with new 
tools. Perhaps most important, specific prob- 
lems were attacked with the aid of a broad 
scientific background. Production engineering 
and processing problems were worked out in 
close cooperation with industry by the loan of 
individuals or groups between the laboratories 
and prospective manufacturers. In this way 
drastic reductions of normal development pe- 
riods were effected and in at least one case full- 
scale production was possible within six weeks 
after the first demonstration of a laboratory 
working model. 

11 2 ASW FROM THE SURFACE 

The problems of locating and successfully 
attacking a submerged submarine are not easy 
ones. The most successful of the methods now 
known are, at best, marginal methods that 
generally operate on the threshold of their 
sensitivity. Any solution is difficult and may 
become ineffective overnight with the introduc- 
tion of countermeasures by the enemy. There- 
fore, various solutions have to be sought. 
Underwater radar would provide an answer, 
except that radio waves can travel only a few 
wavelengths before their strength is dissipated. 
Investigation of the entire available radio spec- 
trum has failed to indicate any favorable trans- 
mission region. Although, with the use of very 
long wavelengths it appears possible to reach 
moderate depths, the instrumental problems 
involved make the design of such equipment 
impracticable. 

Other schemes involving visible and infrared 
radiation have been considered and, in some 
cases, investigated. These, too, have been found 
to have extremely limited range and were there- 
fore discarded. 

Other detection methods have been proposed 
which rely on the local magnetic anomaly re- 


sulting from the submarine’s presence in 
earth’s field. Such methods were extensively 
investigated in World War II, and were incor- 
porated into equipment used by aircraft to 
search large areas at low altitude. These de- 
vices, however, provide an assured range of 
only several hundred feet and are not suitable 
for use aboard surface vessels. 

The most effective method yet discovered for 
the underwater transmission of intelligence in- 
volves the use of acoustic energy or sound. Thus 
in both world wars, sound has provided the 
primary method of obtaining intelligence con- 
cerning submerged submarines. 

Two methods are widely employed — listen- 
ing and echo ranging. Listening methods de- 
pend upon the detectable sound the submarine 
target must make in its operation. 

Unfortunately, at attacking speeds, the lis- 
tening vessel generally makes far more noise 
than the submarine, especially when the sub- 
marine is aware of danger and attempts to 
operate quietly. As a consequence, the use of 
listening favors the submarine rather than the 
surface vessel. To overcome the disadvantage 
of this unfavorable noise ratio, the surface ship 
normally employs echo ranging. 

11,2,1 Modification Program 

Recognizing that complete equipment rede- 
sign is a comparatively long-term job, the NDRC 
group concentrated primarily on a program of 
improvements which could be adapted to the 
production equipment with which the Navy 
would have to fight the submarine war. A num- 
ber of improvements were made which pro- 
vided a more convenient arrangement of equip- 
ment, increased speed and precision of bearing 
determination, better circuit design, increased 
ability to resolve small targets, improved trans- 
ducers, and more convenient test and calibra- 
tion equipment. Some of the more important 
of these are described. 

Sonar Consoles 

As previously mentioned, one of the opera- 
tional difficulties was caused by inconvenient 
location of controls and indicators in the cur- 
rent QC stack. For this reason, one of the first 


ASW FROM THE SURFACE 


179 


tasks assigned to the section laboratories was 
that of developing a physical arrangement of 
equipment components which would permit 
maximum operator efficiency. After a thor- 
ough consideration of the physiological and 
engineering factors, the Columbia University 
laboratory at New London [CUDWR] evolved 
a console arrangement which provided a com- 


for unexpected changes in ship’s heading and 
consequent loss of target contact. 

BDI Systems 

Perhaps the most important single improve- 
ment resulting from this program was the BDI 
developed by the Harvard Laboratory [HUSL] . 
This system permitted the operator to deter- 





r 



Figure 1 . (A) The New London [CUDWR] Mark I improved echo ranging receiving rack. (B) RCA 

Manufacturing Company production unit QGB receiving rack. 


fortable seat for the operator with all of the 
commonly used controls arranged conveniently 
at hand. In addition to the indicators formerly 
furnished, the console incorporated bearing 
deviation indicator [BDI] presentation and 
maintenance of true bearing [MTB], By cou- 
pling the ship’s gyro-compass system to the 
projector training gear so that the operator’s 
control called for true instead of relative bear- 
ing, MTB provided an automatic compensation 


mine with a single echo whether his projector 
was trained to the right, left, or squarely on 
the target. Since the former procedure of ob- 
taining target bearing depended on the method 
of cut-ons and cutoffs in which the bearing is 
formed by defining right and left boundaries 
of the target through successive pinging and 
then splitting the difference, the timesaving 
advantages of BDI are obvious. The Harvard 
BDI scheme utilizes two directional receiving 



180 


ANTISUBMARINE DETECTION EQUIPMENT 


patterns which are divergent but overlapping. 
These patterns are produced by introducing 
electrical phase lags between the segments of 
a single, vertically split projector, so that each 



Figure 2. Closeup of Model X-3 BDI showing 
operating controls and cathode-ray indicator 
face. 

pattern is displaced a few degrees to either side 
of the original acoustic axis. 

These two patterns are represented by two 
electric channels in a comparison amplifier. 
With the projector axis trained directly on 
the target, the echo signal is received with 


equal strength in the two channels. When the 
projector is not aimed directly at the target, 
the signal levels in the two channels differ by 
an amount corresponding to the direction and 
degree of deviation. This difference in level 
is measured and used to deflect the beam of a 
cathode-ray tube indicator thus enabling the 
operator to make a rapid and accurate correc- 
tion. 

Several models of the BDI were developed 
of which one, the X-3, was put into pilot pro- 
duction by HUSL. More than 50 of these units 
were furnished and installed on first-line ASW 
vessels and saw combat service during the 1943 
peak of submarine activity. 

Other units, together with the services of 
laboratory engineers, were furnished to assist 
the commercial production program, under- 
taken by the Astatic and Bogen companies. 

Automatic Gain Control Circuits 

Operation of the echo-ranging equipment 
available at the beginning of World War II 
was generally characterized by a loud burst 
of reverberation signal which gradually died 
away during the remainder of the listening in- 
terval. Although no quantitative data are avail- 
able on the effect of this initial burst of sound 
in reducing the operator’s acuity for a weak 
echo, its occurrence is at least psychologically 
disturbing and represents a serious annoyance 
to other personnel stationed in the vicinity of 
the sonar equipment. Suggestions had been 
made in 1941 for the introduction of variable 
gain amplifiers but no constructive action 
toward this end had been taken prior to the 
fall of 1942. 

Time-Varied Gain [TUG]. At the suggestion 
of two naval liaison officers, HUSL undertook 
the problem of designing a simple circuit modi- 
fication [TVG] which would eliminate the loud 
burst of initial reverberation. Within a few 
hours after laboratory engineers gained access 
to the circuit diagram of the type 775 sonar 
receiver, which was in wide use, a scheme was 
devised for accomplishing this result. A major 
advantage of TVG was the extreme simplicity 
of the modification. Almost all receivers used 
in sonar equipment employed variation of the 
grid bias for gain control, and it was easy to 



ASW FROM THE SURFACE 


181 


arrange to provide the bias voltage from a 
leaky condenser charged through auxiliary 
relay contacts during the transmission interval. 
Variations were made in circuit details to ac- 
commodate TVG to various receiver designs. 

The basic principle of TVG was adopted for 
general use by the Navy and was specified as 
a design feature in all sonar equipment pro- 
cured between December 1942 and the adoption 
of the reverberation-controlled gain [RCG] 
system. 

Reverberation-Controlled Gain [ RCG ]. Two 
auxiliary controls are required to enable a TVG 
circuit to match variable water conditions char- 
acterized by differing amounts of initial rever- 
beration and differing rates of reverberation 
decay. A method of compensating for these two 
variables automatically is afforded by a circuit 
arrangement, the functional characteristics of 
which were suggested to an HUSL staff mem- 
ber by members of a General Electric Company 
research group working on a related project. 
The scheme was called reverberation-con- 
trolled gain because the rate at which the re- 
ceiver gain was permitted to return to normal 
was continuously under the control of the recti- 
fied output of the receiver. 

This type of operation differs in a significant 
way from that of a conventional automatic 
volume control [AVC] system. In an AVC cir- 
cuit the receiver gain is either increased or 
decreased as may be required to hold the out- 
put approximately constant. In the RCG circuit 
a decrease of receiver output corresponding to 
reverberation decay allows the receiver gain to 
increase at a rate determined by a preselected 
time constant, whereas an increase in receiver 
output is prevented from producing a corre- 
sponding reduction in gain. The important ef- 
fect of this distinction between AVC and RCG 
circuits is that RCG preserves the full signal 
contrast between an echo and accompanying 
reverberation, whereas AVC tends always to 
reduce the signal contrast. 

The advantages of RCG over TVG, particu- 
larly in freeing the sonar operator from having 
to adjust (or misadjust) the TVG control, were 
strikingly apparent on demonstration. RCG 
was promptly adopted. It was not considered 
desirable to procure modification kits for con- 


verting previous installations but inclusion of 
RCG as a design feature in all new equipment 
was specified in June 1944. 


Transducers 

A very large amount of research and devel- 
opment was undertaken in the transducer field. 3 
Although the fundamental research, which 
greatly expanded the available knowledge of 
the behavior of transducers and transducer 
materials, is the primary accomplishment, 
mention should be made of the many new 


Figure 3. X-OCP sound gear monitor (produc- 
tion prototype) with B19H transducer. 

transducers designed and constructed for Serv- 
ice use. 

It should be emphasized that the fabrication 
of a transducer having predictable character- 
istics is an art which requires much back- 
ground and experience. More important than 
the actual transducers constructed is the man- 
ufacturing “know-how” which has resulted 
from these programs. The difference between 
a good transducer and one which must be re- 
jected generally stems from some such cause. 

In the course of their programs, each of the 
three major division laboratories, as well as 
the Bell Telephone Laboratories [BTL], found 
it necessary to develop transducers having spe- 
cialized characteristics for particular applica- 
tions. Thus the tubular magnetostriction line 
hydrophone, developed by CUDWR, made pos- 
sible the JP and JT submarine systems, as well 

a Refer to Chapter 9 of this volume and Division 6, 
Volumes 12 and 13. 




182 


ANTISUBMARINE DETECTION EQUIPMENT 


as the radio sono buoys and the depth-charge 
indicators. The HUSL B-19 magnetostriction 
tubular unit saw wide use both in its original 
application as a monitor hydrophone, and as 
a reliable reference standard. The same labora- 
tories provided the small rugged laminated 
stacks that have become production standards 
for use in aircraft-launched acoustic torpedoes. 
The University of California [UCDWR] de- 
veloped many specialized piezoelectric trans- 
ducers having high performance characteristics. 

11,2 ' 3 Sound Gear Monitors 

The OAX Monitor. Immediately following 
the first installations of sonar gear auxiliaries, 
there was a persistent demand for some simple 
device to assess the performance of the equip- 
ment. The OAX sound gear monitor was con- 
structed to satisfy this need. The apparatus 
consisted of a rugged transducer having sub- 
stantially uniform response over the range of 
17 to 26 kc and a compact electronic unit which 
included a tunable oscillator, an untuned am- 
plifier, a calibrated attenuator and meter, and 
a small speaker. This system permitted tuning 
of sonar gear to obtain maximum sound output, 
calibration of output frequency, and maximum 
sensitivity. Used in pairs, the monitors provide 
a simple method of making simple response and 
pattern measurements on projectors. 

The OCP Monitor. Following laboratory de- 
velopment of the OAX, the OCP monitor was 
designed. This extended the frequency coverage 
to the range of 7 to 70 kc. Both of these units 
were put into production after a number of 
prototype models were built by HUSL for use 
by field engineers and base radio materiel 
officers. 

The Dynamic Monitor. The measurements 
which can be made on sonar gear with the OAX 
and OCP monitors are useful in what might 
be termed a point-by-point operation check. 
They do not, however, permit a rapid quanti- 
tative picture of the overall performance of 
the sonar gear under normal conditions of op- 
eration. The dynamic monitor not only per- 
forms this service but also determines the 
‘‘figure of merit ,, of the sonar installation. 

The figure of merit is defined as the ratio in 


decibels of the transmitted intensity at 1 meter 
from the projector to the minimum echo level 
detectable by the gear under prevailing condi- 
tions of water noise. This figure thus allows a 
valid objective comparison between different 
types of gear under the same conditions or the 
same type of gear under different conditions. 

Only one experimental model of this device 
was constructed for local use. However, in view 
of the convenience of this device and the use- 
fulness of the information it makes available, 
strong recommendations have been made for 
further engineering of this instrument in order 
that it can be furnished to experimental, engi- 
neering, and maintenance groups. 

1124 QH-QK Systems 

Along with the short-term improvement pro- 
gram, two of the division’s laboratories under- 
took to develop integrated sonar systems having 
new performance features not available in the 
QC-type sonar equipment. The principal depar- 
ture from previous designs was the provision 
of scanning which permits a more rapid exam- 
ination of a search area than the searchlight 
type of operation provided by conventional 
systems. 

Two types of scanning systems were con- 
structed. The QH systems, developed by HUSL, 
scan rapidly in azimuth and normally in range, 
whereas the QL system developed by UCDWR 
may be considered to scan rapidly in range and 
normally in azimuth. Both systems utilize a 
cathode-ray tube for plan position indicator 
[PPI] presentation of the area surrounding 
the ship. 

Search operations are conducted with stand- 
ard searchlight-type sonar equipment, by scan- 
ning range for a single azimuth bearing and 
successively repeating this process until the 
entire desired area has been examined. With 
radar, the high velocity of propagation makes 
this search program very rapid. The compara- 
tively low velocity of sound in water, however, 
renders sonar search by this method very slow. 
Thus, with a 4,000-yd maximum range and 
5-degree azimuth steps, 6 minutes are required 
to cover the entire 360 degrees. 

The method employed by QH-type sonar over- 


ASW FROM THE SURFACE 


183 


comes this time handicap by irradiating the 
whole horizon with a transmitted pulse of 
sound and then rapidly searching azimuth with 
a listening beam for echoes from distances 
which increase slowly in accordance with the 
low velocity of sound. 



Figure 4. Indicator-control unit, Model XQHA 
scanning sonar. 


As a result of this combination of rapid 
search in bearing and slow search in range, 
each transmitted pulse enables the sonar sys- 
tem to scan the entire horizon out to the range 
within which detection is permitted by the 
water conditions. Thus, searching by sonar is 
possible within time intervals comparable to 


those required for coverage of the horizon by 
radar sets. 

The laboratory development of QH scanning 
sonar involved the study and design of high- 
powered transmitters for generating the in- 
tense sound pulses required to irradiate or in- 
sonify the entire horizon. The essential novelty 
of QH scanning sonar, however, lies in the 
method by which all azimuth bearings may be 
examined rapidly. This method requires the 
production of sharp beams of receiving sensi- 
tivity which can be caused to rotate very rap- 
idly. It is, in fact, necessary for the beam of 
receiving sensitivity to rotate through 360 de- 
grees within a time interval corresponding to 
the length of the pulse of transmitted sound 
in order to insure that some portion, at least, of 
any echo wave train will be received during the 
scanning cycle. 

Commutated Rotation (CR-Sonar) 

Although purely mechanical means of ob- 
taining a rotating beam were investigated, 
a more attractive method of producing a ro- 
tating beam of sensitivity is by control of 
phase and amplitude of the response from 
the individual elements of a cylindrical array. 
A beam can be formed by using the ele- 
ments in a limited arc of a circular array if 
time lags are inserted in the circuits leading 
from the center elements (those closest to the 
sound source) so that the signals are combined 
as though received by elements in a plane. By 
dropping an element from one end of the active 
sector and adding another element at the other 
end (an operation carried out by a multiple 
point switch or commutator) the direction of 
the beam is shifted through an amount equal 
to the angular spacing between the individual 
elements. Experiments proved that if the mul- 
tiple connections were effected by a commutator 
utilizing capacitive coupling, the axis of the 
receiving beam would move smoothly and con- 
tinuously between the successive positions. The 
final development of this series, so far as HUSL 
was concerned, was the commercial commu- 
tator design that formed the basis of the XQHA 
scanning sonar prototype manufactured by the 
Sangamo Electric Company. 

Various details of the scanning equipment 




184 


ANTISUBMARINE DETECTION EQUIPMENT 


required study and analysis before a suitable 
degree of reliable operation could be achieved. 
Studies had to be made of sweep circuits suit- 
able for presentation of target information on 
the PPI, and lag lines had to be designed that 
would have constant delays over a wide fre- 
quency band. Most important of all was the 
design of a multielement cylindrical transducer 
which would have high efficiency and exhibit 
the necessary uniformity of phase and ampli- 
tude from element to element. 

Making the large transducers involved great 
difficulties in theoretical design and required 
the solving of many shop construction prob- 
lems. Progress in the development of the scan- 
ning system as a whole was regulated by the 
achievements of the transducer design group. 

One of the important steps in the develop- 
ment of scanning sonar was the provision of a 
listening channel which can be trained by hand 
to monitor continuously some particular bear- 
ing. In this way, in addition to observing the 
indications on the PPI, the operator can also 
experience the conventional sounds of echo 
ranging and can apply his full training in the 
auditory interpretation of target noise, echo 
character, target doppler, etc. Normal search- 
ing consists of observation of the PPI. Any sus- 
picious indications which might represent echo 
targets can be investigated promptly by train- 
ing the listening channel to a corresponding 
bearing. 

Electronic Rotation (ER Sonar) 

In the electronic systems devised at HUSL a 
phase-advancing network was permanently con- 
nected to each of the transducer elements. This 
formed a lead line closed upon itself with a 
transducer element representing an active 
source connected to each section of the line. 
Signals corresponding to a sharp beam did not 
appear at any single junction terminal of this 
simple network but combinations of signals ap- 
pearing at several adjacent terminals would 
produce such a beam. By connecting a series 
of vacuum tubes or varistors permanently to 
each junction of the network, a receiving beam 
could be made to rotate by activating the 
varistors cyclically with impulses from a switch- 
ing line. The shape and duration of the switch- 


ing pulse controlled the combination of signals 
to produce the directional beam. 

ER for Submarines (XQKA). In general, the 
receiving beams formed in this way were 
broader than would be afforded by the same 
48-element transducer in combination with the 
beam-forming networks of a CR system. How- 
ever, scanning speeds of 350 rps could easily 
be obtained, permitting the use of transmitted 
pulse lengths as short as 3 msec and providing 
excellent range resolution. 

The use of short pulses is especially advan- 
tageous in the detection of small reflecting 
objects, such as mine cases. This feature made 
the ER scanning system especially welcome 
aboard submarines. Three experimental models 
of this equipment designed for submarine in- 
stallations were constructed by HUSL under 
the designation XQKA. The first of these mod- 
els, installed in USS Dolphin at New London, 
indicated a normal detection range of 600 to 
1,400 yd for standard mine cases, with occa- 
sional indications at ranges as great as 2,100 
yd. The typical discovery range appeared ade- 
quate to permit the submarine commander to 
conn his vessel safely through a mine field. 
One of these experimental models was at Pearl 
Harbor for service trials under Naval Research 
Laboratory [NRL] auspices when the war with 
Japan terminated. 

Field Tests 

Demonstrations of HUSL experimental scan- 
ning sonar and, later, of the Sangamo-con- 
structed XQHA equipment evoked uniformly 
enthusiastic response on the part of naval rep- 
resentatives. A directive issued in the fall of 
1944 stated that all “ultimate” sonar equipment 
should include horizontal scanning as a design 
feature. 

Through cooperation of ASDevLant, a team 
of officers, which had carried out an extensive 
series of attack teacher trials for evaluation 
of attack directors for use with searchlight- 
type sonar equipment, made a similar series of 
typical runs with an attack teacher modified 
for instruction in scanning sonar operation. 
One of the questions arising in connection with 
Service acceptance of the QH-type of scanning 
sonar was whether its simple substitution 


ASW FROM THE SURFACE 


185 


for conventional searchlight sonar equipment 
would involve any sacrifice in attack potential. 
The ASDevLant report on these preliminary 
tactical trials set forth the conclusion that in- 
formation from the PPI display of scanning 
sonar could be used about as satisfactorily for 
conning an antisubmarine attack as that from 
searchlight equipment fitted with BDI. A fur- 
ther conclusion was that addition of BDI to 
scanning sonar might be of doubtful value in 



Figure 5. Assembly of elements on experi- 
mental HP-3DS depth-scanning transducer pro- 
posed for use with the integrated Type B sonar. 


view of the relatively satisfactory precision of 
bearing determination from the PPI scope it- 
self. Since the advantages of scanning sonar 
in initial search were taken to be obvious, these 
tests presaged the success of future sea trials 
of scanning sonar under actual operation con- 
ditions. 

Depth Scanning 

In June 1944, HUSL was asked to consider 
the adaptation of scanning sonar principles to 
depth determination and to propose a design for 


a complete sonar system which would include 
azimuth scanning for search and depth scan- 
ning for attack, and that would give stabilized 
information required by fire-control equipment. 
Such a system was proposed, using a two-axis 
stabilized depth-scanning system to obtain fire- 
control information, and was designated by 
the Navy Integrated Type B. Another system 
proposed by the NRL to meet the same require- 
ments, using a three-axis mechanically sta- 
bilized searchlight sonar for obtaining fire- 
control information, was designated Integrated 
Type A. Both systems proposed the use of QH 
azimuth-scanning system. HUSL set up a pro- 
gram which called for (1) theoretical and ex- 
perimental investigations of the possibility of 
depth-scanning itself, and (2) future detailed 
design and development of the complete system. 

The first part of this program called for con- 
siderable research and development work. The 
depth-scanning system, including stabilization, 
was set up and tested on an experimental basis. 
The investigation and experience with azimuth- 
scanning systems led to the general design of 
the integrated Type B sonar, which was par- 
tially constructed, but not completed or tested 
by HUSL. 

Future Development 

Integrated Type B Sonar. HUSL's experi- 
ments on depth scanning were successful to the 
extent that the system operated as expected. 
Reverberation did not appear to be a disturbing 
factor, but the echo from the bottom of the 
ocean was extremely disturbing for both the 
scanning and listening portions of the depth 
system. It was found that bottom echo dis- 
turbance could be minimized by transmitting 
on a directional-type beam rather than on the 
nondirectional beam used originally. 

On the basis of HUSL data, it is recom- 
mended that, in future experiments, the trans- 
mitting beam provide approximately constant 
echo strength from a target at constant depth 
as the range from the ship to target changes. 
Some difficulties also were observed in obtain- 
ing proper depth angles for a target at known 
depth angle. An effort should be made to evalu- 
ate the effects on operation of the system caused 
by the target-image in the surface and by in- 


186 


ANTISUBMARINE DETECTION EQUIPMENT 


homogeneities in the water path between the 
target and the experimental ship. 

The integrated Type B sonar has a number 
of distinct advantages over other sonar gear. 
Original detection of a target by the azimuth- 
scanning portion of the system is obtained by 
watching a single indicator without moving 
any controls. Following detection, placing the 
cursor of the PPI on the target and keeping it 
there allows further detection of the target on 
the elevation position indicator [EPI] without 



Figure 6. Consoles for proposed integrated 
Type B sonar. 


moving any other controls. Use of the BDI 
technique allows continued bearing determina- 
tion even when the target is no longer detecta- 
ble on the azimuth-scanning portion of the sys- 
tem. Continuous maintenance of contact with 
a minimum of effort is thereby accomplished 
from the original detection throughout the time 
that the target remains within detectable range, 
including very short ranges and depth angles 
to 90 degrees. Because of the ability of this 
system to retain contact with the target to very 
short ranges and large depth angles, the conn- 
ing officer should be able to make a better 
judgment of the evasive behavior of the target 


and be able to avoid the uncertainty now ex- 
isting when contact is lost. With the addition 
of a suitable attack director (now under de- 
velopment) to include depth angle in its com- 
putations, the problem of attacks on the target 
should be simplified and, on the average, at- 
tacks should be more successful. Upon avail- 
ability of trainable gun-type ordnance, the 
effect of the first rounds on the target can 
probably be taken into account. 

For navigational purposes, the system could 
be adapted with ease for detection by the PPI, 
of surface ships, buoys, reefs, or other ob- 
stacles near the surface. The EPI could be used 
to examine the bottom in the direction of, or 
at any angle to, the direction of motion of the 
ship, and could also be used to detect submerged 
objects on the bottom or between the surface 
and the bottom for any particular direction. 

11 25 QL Systems (FM Sonar) 

QL-type sonar, the second type of high-speed 
search system, reversed the roles of range and 
bearing determination. In QH systems, differ- 
ent bearings are presented simultaneously while 
range is slowly scanned ; in QL systems, ranges 
are presented simultaneously while bearings 
are slowly scanned. This method of operation 
is accomplished by the use of a frequency- 
modulated transmission signal which irradiates 
a wide sector. A sawtooth modulation is used, 
that is, the frequency decreases uniformly with 
time for a period determined by the maximum 
range setting after which the frequency re- 
turns abruptly to its starting point and another 
cycle begins. The frequency of the returning 
echo obviously follows the pattern of the trans- 
mitted signal, but is displaced in time by the 
interval required for sound to travel out to the 
target and return. The range, therefore, can 
be determined by measuring the constant fre- 
quency difference between the transmission and 
echo frequencies. 

As any particular difference frequency rep- 
resents a particular range, the receiving system 
is provided with a range analyzer comprising 
a series of filters so that echoes from all ranges 
at a given bearing can be portrayed simul- 
taneously on a cathode-ray screen. 


187 


ASW FROM THE SURFACE 


Target information is continuous with the 
exception of a lost-time interval at the begin- 
ning of each sawtooth modulation cycle which 
is equal to the sound travel time to and from 
the target. 

With FM sonar, a continuous signal is sent 
out over a wide sector which in present gear 
is 80 to 90 degrees wide. In practice, the echo 
is heterodyned against the outgoing signal and 
it is the difference frequency which is actually 
used for detection of the echo. Each receiving 
filter responds only to echoes from a certain 
level of range. The relatively narrow width 
of the filters (each 75 cycles wide) results in 
a high signal-to-noise ratio. Gear of present 
design employs a directional, trainable, receiv- 
ing transducer which is rotated mechanically 
so that any given sector can be scanned in a 
fraction of a minute. Since the projector is also 
somewhat directional, it is mounted on the 
same shaft and is rotated with the receiver. 

It was the opinion of UCDWR engineers that 
FM sound offered a number of advantages 
over the conventional types of echo-ranging 
gear utilizing pings or pulses. Principally 
among these were the ability to obtain con- 
tinuous range information on multiple targets 
and a low signal-to-noise ratio by the use of 
narrow receiving filters. The filter width in an 
FM system, combined with the frequency of 
modulation, also determines the equivalent 
pulse length. Thus, the use of narrow filters 
results in a very short equivalent pulse length 
which permits detection of small objects such 
as mines. In attacking the problem, UCDWR 
engineers envisioned a device which would au- 
tomatically delineate the outline of the target 
on the screen of the cathod.e-ray oscilloscope 
[CRO]. The realization of this ideal, although 
possible, was complicated by many factors and 
many of the early systems were primarily con- 
cerned with working out a solution to the prob- 
lem of using FM sound for underwater detec- 
tion, without too much emphasis being placed 
upon the actual portrayal of the target. 

Cobar 

The FM systems program was undertaken 
by UCDWR in the fall of 1941. FM systems 
being studied at this time were designated by 


the name cobar (continuous bearing and 
range) . A number of these experimental sys- 
tems were assembled. Although cobar systems 
afforded a high degree of range resolution, 
their ability to scan range rapidly was limited 
by the fact that they searched range in a sin- 
gle annular ring whose radius is adjustable. 
Cobar’s high degree of range resolution led to 
a fire control modification known as subsight 
which furnished “time-to-fire” information for 
forward-thrown weapons. The system included 
automatic compensation for the range error 
introduced by doppler shift. 

The continuous nature of the information 
provided by cobar, combined with its high de- 
gree of range resolution and good signal-to-noise 
ratio, led to investigation of its use in small- 
object (mine) detection. The capabilities of 
cobar in this application were demonstrated to 
the Navy at Norfolk, and created considerable 
interest as early as June 1943. 

Pribar 

Early in the cobar development, February 
1942, a modification under the designation pri- 
bar was made which introduced the use of a 
CRO screen for target presentation. The pribar 
systems employed a fixed-position multielement 
hydrophone. Phasing networks connecting the 
various elements of this hydrophone caused its 
sound beam to scan in bearing as a function of 
frequency. Increased speed in range scanning 
was sought by injection into the receiver of a 20-c 
sine wave modulation which was superimposed 
on the basic sawtooth frequency and which 
made it possible simultaneously to scan ranges 
from zero up to the maximum range for which 
the system was set. 

Fampas 

Cobar systems and their modifications, sub- 
sight and pribar, employed a single narrow 
band-pass amplifier. It was realized, however, 
even during work with the early cobar systems, 
that all range information necessary for the 
simultaneous portrayal of multiple targets at 
any range from zero to the maximum range 
setting was present in the system’s first detec- 
tor, if only some means could be devised for 
making it available in readily intelligible form. 


188 


ANTISUBMARINE DETECTION EQUIPMENT 


In January 1943, a multichannel analyzer 
and electronic switch were developed which 
made possible this type of target presentation 
with the FM systems. Systems using the ana- 
lyzer and multichannel switch were, at first, 
designated fampas (frequency and mechani- 
cally plotted area scan) and gave a PPI plot 
presenting a plan view of the area surrounding 
the echo-ranging vessel. 

During work on fampas-type sonar, the des- 
ignation was changed to FM sonar and under 


interested in FM sonar as a prosubmarine de- 
vice for use in heavily mined enemy waters. 
Ten FM systems were ordered for installation 
in submarines operating in Japanese waters, 
and during the construction of these units, the 
Navy designation QLA sonar replaced the older 
FM sonar. In the summer of 1945, nine subma- 
rines equipped with QLA gear entered the 
mined waters of the Japanese Sea, and all but 
one of these vessels obtained contacts on mines, 
while all nine submarines were able to avoid 



Figure 7. FM sonar equipment of type used on USS Spade fish installation. 


the name of FM sonar Model 1, a system was 
tested at New London in which ranges on a sub- 
marine up to 3,200 yd were obtained. 

Until late fall of 1943, the FM system had 
been regarded primarily as an antisubmarine 
device. However, with the relatively successful 
progress of antisubmarine warfare, the em- 
phasis was changed to utilization of the FM 
system as a small-object detection device, and a 
model was tested for detection of small objects 
in shallow water. 

Subsequent tests led to improvements in de- 
sign and installation, and the Navy became 


the mines safely with the aid of QLA informa- 
tion. Later, comparison of the plots of the mine 
contacts obtained by these submarines per- 
mitted the preparation of a chart showing the 
character and location of the mine field. After 
the end of World War II, these charts were 
found to be in good agreement with those of 
the Japanese Navy. 

Further Development 

The QLA-1 sonar device does not represent 
the ultimate in FM techniques or possibilities; 
but rather, a stage in FM systems development, 



ASW FROM AIRCRAFT 


189 


tempered by expediency and the need for pro- 
duction of a device which would be of assistance 
during World War II under particular and pe- 
culiar circumstances. 

The future development trend of FM sonar 
is being directed toward the ability to obtain 
target information faster, more accurately, and 
in greater quantities. The present system scans 
range rapidly and provides a simultaneous 
PPI-type portrayal of multiple targets on any 
given bearing. Target information, however, is 
limited by: 

1. The indicated range error resulting from 
doppler shift. 

2. The momentary break in target informa- 
tion during the lost-time interval. 

3. The limited rate of bearing scan (6 rpm) 
determined by the width of the transmitted 
sound beam. 

The proposed development program includes 
means of eliminating these limitations as well 
as the addition of new functions to the system. 

The range error due to doppler may possibly 
be corrected by combining a pinging system 
with the FM system in such a way as to give 
true range as well as continuous range rate in- 
formation which could be used for fire-control 
applications. 

The problem of eliminating lost time has 
already been solved. By the use of a nondirec- 
tional projector, the bearing scan rate can be 
increased from 6 to 120 rpm before the build- 
up time in the analyzer filters becomes a con- 
trolling factor. Depth determination has in- 
creased importance when one considers the 
high speeds and great operating depths of 
future submarines. The addition of a second 
stabilized sound head rotated 90 degrees and 
scanning in the vertical plane would provide 
depth angle and slant range information which 
can easily be converted to true depth. Such in- 
formation would also be of considerable value 
to FM equipped submarines in determining the 
depth of mine fields. 

Bearing accuracy may be increased by the 
use of a BDI system and range accuracy by 
increasing the number of filters used to analyze 
the frequency difference between the transmit- 
ted signal and returning echo. 

A possible improvement in indicators which 


should be tried and evaluated for its tactical 
value involves the use of dark-trace cathode- 
ray tubes or skiatrons. With such tubes, it is 
possible to project, greatly enlarged, a PPI trace 
on a plotting board. With tubes of ordinary 
dimensions, the trace can be enlarged to a 
diameter of at least 30 inches. Such a plot com- 
bined with depth information fed automati- 
cally to the plotting board might make target 
information available to the conning officer in 
a form more quickly interpretable. 

The use of FM systems as passive listening 
as well as echo-ranging devices for torpedo 
detection should also be investigated in face 
of the extensive use of homing weapons to be 
expected in the future. 


11 3 ASW FROM AIRCRAFT 

During the period just before the United 
States entered World War II, it became increas- 
ingly clear that aircraft should possess certain 
characteristics that would make them effective 
in antisubmarine warfare. Aircraft are valu- 
able for searching operations because of their 
long-range and high-speed capabilities, and be- 
cause, after locating a submarine, they are 
able to deliver an explosive charge on it. On the 
other hand, their limitations were equally clear. 
At that time, aircraft could be used to locate 
surfaced submarines visually or by radar, but 
they were not capable of detecting submerged 
submarines, nor could they follow the course 
of a submarine after it had submerged. Fur- 
thermore, existing ordnance was effective only 
when direct hits were obtained. Consequently, 
to be effective in antisubmarine warfare, both 
the detection systems and ordnance used by 
aircraft had to be improved. 

The introduction of aircraft in antisubma- 
rine warfare did much to change the emphasis 
from defensive fighting to offensive fighting, 
by making possible an extension of the search 
area. Submarines could be attacked before they 
were close enough to threaten ships. Later, 
when effective radar detection was added to 
visual detection, the sweep rate was further in- 
creased. 

The advent of Schnorchel, however, drasti- 


190 


ANTISUBMARINE DETECTION EQUIPMENT 


cally reduced the aircraft's search capabilities, 
because the radar sweep width on Schnorchels 
is much less than on surfaced submarines. As 
the use of Schnorchel made it possible for 
enemy submarines to remain submerged for 
longer periods, there was an urgent need to de- 
velop a satisfactory means for detection and 
location of Schnorchel and totally submerged 
submarines. 

Section C-4 of the NDRC undertook investi- 
gations of existing airborne detection systems 
and, after some research, found that two dif- 
ferent physical methods, magnetic airborne de- 
tection and radio sono buoys, promised prac- 
tical results. Development work was then un- 
dertaken to improve the effectiveness of these 
two systems. 


Magnetic Airborne Detector 

The magnetic airborne detector [MAD] is a 
device designed to locate a submerged subma- 
rine from aircraft by detecting the magnetic 
anomaly set up by the ferromagnetic mass of 
the submarine. 

In the spring of 1941, the need was urgent 
for a means of detecting a submerged subma- 
rine from aircraft. The British were attempt- 
ing the development of magnetic airborne gear 
which, under favorable conditions, proved ca- 
pable of detection at ranges no greater than 200 
ft. This figure was clearly too low to be of op- 
erational value. A more promising line of de- 
velopment appeared to lie in improving the sys- 
tems already in use in the United States for 
geophysical prospecting, which utilized a satu- 
rated-core magnetometer. 

If a sine wave a-c voltage is applied to a coil 
surrounding a strip of permalloy, the metal 
will saturate magnetically at the peak of every 
cycle of the alternating current. The self -induct- 
ance of the coil will, therefore, vary during the 
cycle and so the waveform of the resulting cur- 
rent through the coil will be rather complex. 
Any slight external magnetic field also acting 
on the permalloy, parallel to its length, will in- 
crease or reduce the amount of current in the 
coil needed to cause saturation, and so will 
change the point in the a-c cycle at which satu- 


ration occurs. This, in turn, results in a slight 
but characteristic alteration in the waveform 
of the current in the coil. If the device is con- 
nected to an amplifier which is sensitive to 
changes in the waveform of this current, it be- 
comes an indicator of any external magnetic 
field having a component parallel to the permal- 
loy strip. 

To measure the magnetic field a magnetom- 
eter is employed. The Gulf Research and De- 
velopment Company had produced an instru- 
ment known as the Vacquier magnetometer 
which when completely developed proved to be 
well adapted to the purpose of submarine detec- 
tion. 

The magnetic field of the earth is defined by 
magnitude and direction, that is, it is a vector 
quantity. Because of this, any rotation of the 
magnetometer due to motion of the plane will 
cause a change in magnitude of the magnetic 
flux through its coils which does not correspond 
to actual change in the magnetic field. These 
disturbing magnetic effects, or spurious sig- 
nals, must either be neutralized or the relative 
motions eliminated. Means had to be devised to 
maintain the magnetometer in a definite direc- 
tion in space. Early models used gyroscopes to 
secure stabilization, but this solution was in- 
adequate, and later models employed magnetic 
stabilization. 

The signals or pulses produced by the mag- 
netometer must be converted into other signals 
suitable for recording and interpretation. 
There are various ways to record these signals, 
the common one being a record secured as a 
line on a continuously moving tape. 

In the installation and operation of MAD, it 
is necessary to avoid spurious signals produced 
by magnetic fields associated with the aircraft 
itself. One means was to locate the equipment 
away from metal parts or tow it behind the 
plane. Another means was to provide magnetic 
compensation for these local fields. 

The major problems were solved to the ex- 
tent that the detection equipment finally devel- 
oped has a background noise level of about 0.2 
gammas under conditions of reasonably 
straight flight in a magnetically quiet area. If 
the magnetic fields due to the aircraft itself are 
properly compensated, the spurious signals re- 


ASW FROM AIRCRAFT 


191 


suiting from rapid plane maneuvers are not 
over a few gammas. Thus the equipment is ca- 
pable even in flight of detecting a submarine 
where the magnetic anomaly produced by its 
presence is only a few gammas. Present maxi- 
mum range of MAD equipment is about 600 ft. 

AN/ASQ-1 

The first instruments tested, the Mark I and 
Mark II, used a gyro stabilization and employed 
a Vacquier saturated-core magnetometer. The 
subsequent models, Mark IV and Mark IV B-l, 
and the resulting production models, Mark IV 
B-2 and AN/ASQ-1, were based on magnetic 
stabilization of the magnetometer head without 


World War II to receive much combat test. Be- 
tween July 1941 and July 1944 about 400 in- 
stallations of MAD equipment were made and 
proved useful in cases where aircraft located a 
submarine visually or with radar and the sub- 
marine submerged before the aircraft could 
reach it. The MAD was also used in maintain- 
ing blockade patrols of small strategic areas. 
During the last part of World War II, however, 
the MAD was largely supplanted by the radio 
sono buoy. 

Future Development 

The MAD equipment suffers inherently from 
the handicap of limited range and in certain 



Figure 8. (A) MAD installation on wing of PBY-5A. (B) A tailcone installation. 


the use of a gyroscope. The final, improved 
model, AN/ASQ-1, was ready for service in 
December 1942, but later an improved univer- 
sal magnetometer head was developed to per- 
mit operation at any magnetic latitude. This 
equipment was designated as AN/ASQ-1A. 

AN/ASQ-2 

In 1943, two automatic units to facilitate the 
dropping of flares and bombs were perfected. 
One of these is an automatic flare or bomb re- 
lease unit, CP-2/ASQ-1, to be used with the de- 
tection of targets. The other is a magnetic 
airborne bombsight designed to determine the 
lateral position of the target with respect to the 
aircraft and to release bombs automatically 
only if the aircraft is within proper range. This 
unit, CM-l/ASQ-2, is used with dual installa- 
tions of the detection equipment. 

About 50 of these dual automatic installa- 
tions were made but they came too late in 


areas, its effectiveness may be further limited 
by geological conditions. The present range of 
not over 600 ft probably cannot be markedly 
increased. Studies have indicated that present 
gear accomplished about all that conditions 
will permit. However, if in the future this 
method appears to have promise, certain re- 
finements of design should be undertaken. Even 
if the future submarine is increased in size and 
has a larger magnetic moment, the most highly 
developed forms of MAD will probably be re- 
stricted to areas where the submarine cannot or 
does not operate at great depths of submer- 
gence. Since conditions of future warfare are so 
problematical, MAD should not be discarded as 
a potential tool. 

Although MAD AN/ASQ-1 was developed 
for submarine detection, its usefulness is not 
limited to this single objective. Investigations 
were made of the possibility of detecting mech- 
anized field equipment, fixed gun emplace- 


192 


ANTISUBMARINE DETECTION EQUIPMENT 


ments, munition factories, and other land tar- 
gets. Also, the possibility of using AN/ASQ-1 
equipment for navigation of bombers to their 
targets was briefly investigated. The tests were 
encouraging, but further development work 
must be done to improve the effectiveness of 
MAD equipment for these purposes. 


11 3 2 Radio Sono Buoys 

The radio sono buoy is a device designed to 
allow remote detection of sounds in water. 
These sounds are picked up by the buoy hydro- 
phone and broadcast by radio to a receiving 
station located aboard a ship, airplane, blimp, 
or on shore. 

The Expendable Radio Sono Buoy 

The first device to be put in operational use 
was the expendable radio sono buoy [ERSB]. 
This device, also designated AN/CRT-1A, con- 
sists of a sonic listening hydrophone and ampli- 
fier coupled to a frequency-modulated radio 
transmitter. These elements and a battery 
power supply are incorporated in a water- 
proof cardboard tube about 30 in. long and 4 
in. in diameter, weighing about 12 lb. 

The buoy is dropped from an airplane or 
blimp by means of a self-contained parachute. 
Upon striking the water, an impact catch re- 
leases the hydrophone which sinks to a water 
depth of about 20 ft, the length of the support- 
ing cable. The buoy transmitter operates on 
frequencies between 67 and 72 me and has a 
maximum range of about 35 miles when the 
listening aircraft is at an altitude of 5,000 ft. 
The operating life is from 2 to 4 hours after 
planting, after which a plug is dissolved and 
the device sinks. The aircraft receiver is pro- 
vided with six frequency channels (later 
twelve) which allows the simultaneous use of a 
like number of buoys. 

With this device, a submerged submarine 
can be kept under aural observation, oil slicks 
can be investigated, and damage to a subma- 
rine during attack can be ascertained. It is also 
possible to track a moving submarine by using 
several buoys simultaneously. Some evidence of 
the effectiveness of the ERSB is indicated by 


the fact that more than 160,000 units were 
ordered. 

Experience showed, however, that the buoy’s 
functions could be more effectively performed 
if a buoy could be developed which would be 
capable of broadcasting not only underwater 
sounds, but also the direction from which these 
sounds came. Tactical operations could be im- 
proved, observation time would be reduced, and 
space in aircraft would be saved. Because the 
suggested improvements would increase the 
weight and bulk of the existing buoy, a general 
redesign was required. 

The Directional Radio Sono Buoy [DRSB] 

The DRSB consists of a directional sonic lis- 
tening hydrophone which rotates continuously 
to provide 360 degrees scanning in a horizontal 
plane around the buoy, together with a sonic 
amplifier, rotating mechanism, and frequency- 
modulated radio transmitter. The system, in- 
cluding battery power supply, is incorporated 
in a tubular buoy of bakelite impregnated 
paper about 52 in. long, 6 in. in diameter and 
weighs about 30 lb. It also is dropped with a 
self-contained parachute. 

Transmission of directional information is 
accomplished by means of a compass-capacitor 
which causes the center carrier-frequency of 
the radio transmitter to vary with the rotation 
of the buoy. The aircraft receiver is provided 
with a circuit to translate these changes in 
transmitting frequency into directional indica- 
tions which appear on a meter. The DRSB 
proved effective in tests and 7,000 units were 
ordered. 

Although ERSB and DRSB were designed 
for use from aircraft, they were also often 
launched from surface ships. Both systems 
played a major part in antisubmarine warfare 
listening. 

Aircraft used sono buoys more frequently to- 
ward the end of World War II, and analysis in- 
dictated that in over 50 per cent of the cases 
in which sono buoys were dropped, following 
visual contact, a sono buoy contact was ob- 
tained. Sono buoys were thus responsible for 
establishing and maintaining underwater con- 
tacts that led to the destruction of many enemy 
submarines. 


HARBOR PROTECTION 


193 


However, a number of improvements would 
make the device more effective. Foremost 
among these is the provision for improved di- 
rectional indications to enable more accurate 
location of submerged targets, as well as longer 
listening ranges and the use of fewer buoys. It 
is also desirable to double the number of fre- 
quency channels for the nondirectional buoys, 



Figure 9. The directional radio sono buoy in 
water showing marker dye bog and dye trace. 


to provide for connecting receiver output di- 
rectly into the plane's intercommunication sys- 
tem, and to develop containers for marker dyes 
which will dispense the dyes on water impact 
but will not break in normal handling. 

114 HARBOR PROTECTION 

Wartime protective barriers for inner harbor 
areas are formed by mine fields, submarine 


nets, magnetic loop cables, and other fixed ob- 
structions. These barriers are generally supple- 
mented by armed patrol craft. However, none 
of these barriers is capable of indicating the 
actual location of harbor intruders, although 
magnetic loop cables can detect the presence of 
an intruder when it crosses the loop at the sea- 
ward end of the harbor. But magnetic loop 
cables cannot indicate the actual position of an 
intruder. 

There was a need consequently for a harbor 
protection system which would indicate both 
the presence and location of approaching in- 
truders of any size. The Navy had done basic 
development work, and proposed the cable-con- 
nected hydrophone system and the anchored 
radio sono buoy as sonic methods of detecting 
and locating harbor intruders. Several NDRC 
laboratories undertook assisting investigations 
of these two systems to develop them for prac- 
tical use. 

Anchored Radio Sono Buoy 

The anchored radio sono buoy [ARSB], 
anchored in a harbor as a part of the harbor 
protection system, picks up underwater sounds, 
amplifies, and impresses them by means of fre- 
quency modulation upon a radio carrier trans- 
mitting them to shore receiving stations. At the 
listening posts are radio receivers attended by 
listeners trained to distinguish the sounds of 
submarines and various types of surface craft. 
When these buoys are placed in strategic loca- 
tions, they make possible the continuous moni- 
toring of underwater sounds in the nearby 
area. They are reserved for use in deep water 
and for auxiliary or emergency use at advance 
bases, where the expenditure of time, material, 
and effort such as needed for a cable-connected 
hydrophone system would not be justified. 

CUDWR collaborated with NRL in a pro- 
gram of tests and development on two experi- 
mental models. The first model, JM, provided 
two buoys, one a transmitter buoy from which 
the hydrophone was suspended, and a separate 
anchor buoy to prevent cable fouling. Electrical 
equipment consisted of a dry cell power supply, 
a medium gain audio amplifier, FM carrier- 
wave system and a half-wave antenna. The sec- 
ond model, JM-1, incorporated the desirable 



194 


ANTISUBMARINE DETECTION EQUIPMENT 


features of JM and included new features such 
as heater-type tubes, high audio gain, low mi- 
crophonics, and pre-emphasis on high frequen- 
cies. The final JM-1 model operated satisfac- 
torily at an 8-mile radio range and, under fa- 
vorable weather conditions, equaled the cable- 
connected system in acoustic performance. The 



Figure 10. The JM-1 anchored radio sono buoy. 


buoy itself could not withstand severe storms. 
Suggestions for further research include im- 
provement of stability, incorporation of all 
components in one streamlined buoy, improve- 
ment of low-frequency response, decreasing 
background noise, and inclusion of a device to 
enable alternative directional and nondirec- 
tional use of the hydrophone. 

Cable-Connected Hydrophones 

After investigation of existing and proposed 
systems, cable-connected listening hydrophones 
appeared to offer the best possibilities for use 
as a secondary detection system for harbor 
protection, since they are capable of detecting 
and determining the approximate location of 
an enemy submarine or surface craft. 


The cable-connected hydrophone system, as 
jointly developed, consists of a series of regu- 
larly spaced, tripod-mounted, crystal hydro- 
phones, connected by a submarine cable to a 
shore station, where a switching mechanism 
and a sonic listening amplifier are provided. 
The switching mechanism automatically selects 
the separate hydrophones for listening during 
an adjustable interval of 2 to 10 seconds. The 
amplifier has a uniform frequency characteris- 
tic over the range of 70 to 12,000 c and pro- 
vides for monitoring either by headphone or 
loudspeaker. 

To be effective, hydrophones must be spaced 
to insure overlapping of effective detection 
areas, and locations must be carefully selected 



Figure 11. Cable-connected hydrophone and 
tripod assembly. 


where favorable listening conditions exist in 
the seaward direction and along the cable. 
When a number of spaced hydrophones are 
available for successive listening, because of 
the character of underwater sound, they pro- 
vide information concerning the vessel’s loca- 


SMALL-OBJECT DETECTORS 


195 


tion and direction of travel. In order to make 
full use of the potential sources of information, 
the system provides high-quality reproduction 
at the listening station, well-balanced sensi- 
tivity among the various channels, and free- 
dom from noise interference. Suitable filters 
are incorporated in the amplifier to discrimi- 
nate against certain types of ambient noise, 
such as that made by fish. 



Figure 12. Anchored vessel screening console, 

HUSL model. 


The installation at Cape Henry, Virginia, 
consisted of 14 tripod-mounted hydrophones, 
spaced 1,000 yd apart along an armored cable 
beginning at a point about 5 miles offshore 
and terminating at the shore listening station. 
Listening ranges of over 7,000 yd were attained 
for surface ships. Since the construction of the 
Cape Henry system a number of means of im- 
proving or simplifying the performance of the 
system have been devised. The size and com- 
plexity of the system has limited its use to con- 
tinental harbors of the United State§. 


11 5 SMALL-OBJECT DETECTORS 

Conventional echo-ranging and sonar gear 
used by the Navy, being primarily designed for 
detecting large objects, was not well-adapted 
for the detection of smajl objects, such as 
midget submarines. When the course of World 
War II made it advisable to develop such small- 
object detectors for harbor protection and 
other purposes, both British and American 
laboratories undertook theoretical and experi- 
mental investigations to determine design fac- 
tors characterizing a high-performance small- 
object system. Experience showed that because 
of the low level of noise generated by small ob- 
jects, direct listening was ineffective. Although 
existing echo-ranging equipment was not suit- 
able, the echo-ranging principle appeared adapt- 
able to small-object detection. 

Anchored Vessel Screening 

The first problem assigned was that of pro- 
ducing a small echo-ranging device as nearly 
automatic as possible, and capable of present- 
ing a continuous picture of the location of all 
underwater objects, down to the size of a 3-ft 
sphere within a 300-yd range at a maximum 
depth of 60 ft. The precision in azimuth was 
originally set at about 10 degrees. 

The BTL System 

The anchored vessel screening system [AVS] 
Mark III, was proposed by BTL as a means of 
protecting ships at anchor from miniature sub- 
marines and small manned torpedoes. This 
echo-ranging device comprised (1) a vertical 
line projector, (2) a receiving hydrophone to 
give azimuth bearing of target echoes over 360 
degrees of azimuth, and (3) electronic circuits. 
Presence of the target is indicated by a bright 
spot on the screen of a cathode-ray tube which 
presents a map of the region around the ship 
with a bright spot in the relative position of the 
target. This system operated as expected in 
tests, although the need for better signal-rever- 
beration ratios was indicated. 

The HUSL System 

The AVS system developed by HUSL is a 


196 


ANTISUBMARINE DETECTION EQUIPMENT 


semiautomatic echo-ranging system, operating 
as acoustic analogue of search radar, with each 
bearing being searched successively in range. 
The CRO screen gives a map of surrounding 
territory but by means more mechanical than 
the BTL model. This unit also provides an 
audible indication. Two models were con- 
structed and performed according to expecta- 
tions. With Navy interest in this problem lag- 


ing characteristic, differentiating small-object 
systems from conventional systems. 

11 ‘ 5 ' 2 Mine Detectors 

Faced with the problem of detecting mine- 
fields from submarines, interest in the detec- 
tion of small objects was renewed and the 
UCDWR was assigned a long-term program 



Figure 13. Recorder traces of typical targets obtained with preliminary model SOD, in San Diego harbor 
test. 


ging, both programs were dropped in favor of 
more urgent work. 

British 135 ASDIC 

The British meanwhile, developed the 135 
ASDIC system, to serve as a harbor protection 
unit capable of detecting midget submarines. 
This system was based on the principle that for 
maximum echo to reverberation ratio, the length 
of the pulse train in water should generally ap- 
proximate the dimensions of the target. Thus, 
a 3-ft target would correspond to a pulse length 
of 0.6 msec. This factor of pulse length ap- 
peared to be the most important single operat- 


devoted to a fundamental determination of 
physical factors affecting performance of 
small-object systems. Concurrent with this pro- 
gram of investigation, several short-term 
equipment developments were instituted. 

Mine and Torpedo Detection System 
[MATD] 

CUDWR, convinced that modification of 
existing submarine sonar installations was 
practicable, proposed certain modifications in 
the standard WCA-2 installation. These in- 
cluded the provision of a short transmission 
pulse which, in turn, required changes in the 






SMALL-OBJECT DETECTORS 


197 


keying and transmitter circuits and the re- 
corder. Experiments with this system, desig- 
nated mine and torpedo detection system 
[MATD], indicated good performance on a 
3-ft mine case out to the maximum indicator 
range of 600 yd. In addition, the feature of tor- 
pedo detection was incorporated by providing 
for continuous rotation of the listening hydro- 
phone with a radial deflection cathode-ray in- 
dicator tube. 

An experimental installation of MATD saw 
active service during the war in the Pacific. 

San Diego Unit 

Several laboratory models of a high-perform- 


ance small-object system were designed and 
constructed by UCDWR, San Diego, California. 
These units generally combined the earlier 
work of British laboratories together with cer- 
tain improvements in transducer design and 
pulse modulation. The SOD 501 using a pulse 
variable from 0.1 to 3.0 msec, with a special 
ADP crystal transducer and a chemical re- 
corder modified to have a slow paper speed, 
achieved maximum ranges of 1,500 yd under 
good conditions. One experimental installation 
was in an operational fleet-type submarine op- 
erating in the Pacific. Further development 
work on this program is continuing at the 
Naval Electronics Laboratory in San Diego. 


Chapter 12 


PROSUBMARINE EQUIPMENT 

By John S. Coleman 


121 INTRODUCTION 

B y the summer of 1943, the successes 
achieved against U-boats in the Atlantic 
and a comparative absence of enemy submarine 
activity in the Pacific made possible a concen- 
tration of effort toward aiding U. S. subma- 
rines. Conferences were held with NDRC rep- 
resentatives and the Navy, which culminated in 
the establishment of a program of prosubma- 
rine development by Division 6. The program 
was assigned to the U. S. Navy Radio and 
Sound Laboratory at San Diego and the U. S. 
Navy Underwater Sound Laboratory at New 
London. 

Antisubmarine projects which could not be 
completed in time to contribute effectively 
against enemy submarines were therefore set 
aside or carried at low priority, and a transi- 
tion phase began which resulted in the labora- 
tories turning the major part of their effort to- 
ward the development of prosubmarine appa- 
ratus and preparation of training programs for 
the assistance of submariners. 

Because of the urgency for development and 
improvement of antisubmarine equipment dur- 
ing the first part of the war, development and 
improvement of prosubmarine equipment had 
been somewhat neglected. Consequently, it be- 
came necessary to develop and improve equip- 
ment for (1) aiding evasive tactics, (2) record- 
ing and eliminating self noise, (3) detecting 
and locating mines, torpedoes, and depth 
charges, and (4) communicating internally and 
between boats. 

The prosubmarine program included the de- 
velopment of new-type submarine listening 
equipment, developing internal and underwater 
communications systems, conducting noise-re- 
duction studies, and modifying other equip- 
ment to new or expanded functions. 

At this time, most fleet-type submarines were 
equipped with supersonic bottomside listening 
gear only. In the spring of 1942, exploratory 
work on sonic listening led to the experimental 
installation of a sonic magnetostriction hydro- 


phone on an older submarine previously 
equipped with a topside training gear. The re- 
sults obtained and the tactical advantages in 
target detection and approach seemed to justify 
the development of a simple directional sonic 
listening gear designed primarily for evasion 
tactics. A number of experimental units were 
tested and proved satisfactory, leading to a final 
design which was made available to the Navy 
in 1943. This gear designated by the Navy as 
JP-1 sound receiving equipment is now stand- 
ard on all U. S. submarines. 

A number of other projects stemmed from 
this beginning. The JP-1 was used on patrol 
to reveal the existence of noise on the subma- 
rine itself, noises which might also be detected 
by enemy listening gear. Later a simple, perma- 
nently installed noise level monitor [NLM] was 
developed to give accurate measurement of 
ship’s own noise while on patrol. 

By August another application of sonic lis- 
tening utilizing JP-l-type components yielded 
a system capable of giving an underwater 
range of a target ship by triangulation tech- 
niques. This system known as triangulation- 
listening-ranging [TLR], was carried to the 
stage of prototype construction by a commer- 
cial manufacturer. As experience with JP-1 
and the TLR experimental models accumulated, 
plans were formed for a greatly improved JP-1 
system affording greatly improved features. 
This system, designated JT, was accepted and 
was being installed on all JP-1 equipped sub- 
marines. 

Requests were also received by the division 
and its laboratories to assist in the task of im- 
proving existing submarine sonar systems and 
in particular, adapting them to the functions of 
torpedo and mine detection. A study was made 
of possible design modification in the WCA-2 
system. As a result, a number of recommenda- 
tions were made which led to the design and 
construction of 12 experimental conversion 
units [MATD]. Also, the Bell Telephone Lab- 
oratories [BTL] were commissioned to engi- 
neer a complete, integrated system having 


198 


SONAR SYSTEMS 


199 


higher performance characteristics, greater 
flexibility in operation and capable of listening 
and echo ranging over a very wide range of fre- 
quencies. An experimental model of this system 
identified as 692 sonar was constructed but had 
undergone only preliminary sea trials at the 
end of World War II. 

Although the scanning sonar systems, de- 
scribed in Chapter 11, had originally been con- 
ceived as antisubmarine equipment, it should 
be noted that they proved to be very adaptable 
for submarine service. In particular, the QLA 
system, developed by the San Diego laboratory 
and installed on fleet-type submarines is 
credited with making possible a successful in- 
vasion of the Sea of Japan. 

High performance reports have also been re- 
ceived by HUSL from an experimental XQHA 
installation. 


SONAR SYSTEMS 


12 2 1 JP and JT Listening Equipment 

The JP-1 equipment provides a sonic listen- 
ing system covering the audible spectrum from 
100 to 12,000 c. It employs a 3-ft straight tubu- 
lar magnetostriction hydrophone mounted in a 
baffle which reduces response to sounds arriv- 
ing from the rear. The hydrophone and baffle 
assembly is rotated by a through-the-hull top- 
side hand-operated training gear which is op- 
erated from a station in the after end of the 
forward torpedo room. An amplifier is provided 
which receives power from the submarine’s 
main batteries. This insures operation as long 
as the submarine has battery capacity. The am- 
plifier is equipped with magic-eye visual indi- 
cator, filters for selecting various bands in the 
sonic spectrum, a special detector circuit which 
aids counting of propeller revolutions, and 
headphones or a loudspeaker for direct listen- 
ing to target sounds. Information thus obtained 
can be relayed to the conning tower via an im- 
proved battlephone system. The hydrophone 
training gear is designed to prevent the possi- 
bility of binding at evasion depths. About 110 
JP-1 equipments were procured, to which were 


later added 150 JP-2 and 50 JP-3 installations. 
The three systems are identical in performance. 

The performance of the JP-1 system proved 
to be very satisfactory. The average initial de- 
tection range reported during patrols was 
about 12,000 yd, although ranges as great as 
40,000 yd were reported. Targets were heard 
with JP-1 gear at ranges greater by an average 
of 50 per cent than the submarine’s supersonic 
equipment. The equipment has also been used 



Figure 1 . JP-1 hydrophone installation. 


for detecting own-boat noise. It is also possible 
to maintain reasonably accurate bearing con- 
tact with surface vessels running overhead. 

At the time JP-1 gear was being installed, 
studies of possible improvements were carried 
out. A number of improvements were made and 
included in the JT modification, along with 
others described in the following section. 

Among the improvements made on JP-1 gear 
were the following. 

1. Development of a system providing the 
approach officer with means for directly ob- 
serving the hydrophone bearing, for listening 
to the hydrophone signals, and for communi- 
cating directly with the JP-1 operator. This 


200 


PROSUBMARINE EQUIPMENT 


system, the bearing and sound repeater, in 
effect makes the JP-1 operator a part of the 
conning tower attack team, although he re- 
mains in the forward torpedo room. 

2. Development of a converter for detecting 
any enemy communication or echo-ranging sig- 
nals in the supersonic spectrum. 

3. Improvement of listening amplifiers 
which incorporate all the desirable features of 



Figure 2. Triangulation-listening-ranging sys- 
tem. 


JP-1, NL-118A, and NLM, plus certain added 
features. 

4. Provision of a 5-ft hydrophone for better 
range and bearing accuracy. An improved baffle 
was also designed and a rubber shock-mounting 
for the hydrophone and baffle was developed 
which helped to isolate the hydrophone from 
the mechanical vibration of the submarine hull 
and to reduce interference. 

In the spring of 1944, it was recognized that 
the improved features could be engineered into 
existing submarines as modifications of the 
JP-1 gear. Active development work was un- 
dertaken and the system was designated as 
Model JT sonar system. 


12.2.2 Triangulation-Listening-Ranging 

In 1943, the New London Laboratory gave 
consideration to a possible future time when 
submarines would be exposed increasingly to 
improved enemy ASW operations both from 
aircraft and surface ships, especially with ef- 
fective radar. Likewise, it was recognized that 
submarines are hampered by the necessity to 
refrain from echo ranging because of the 
danger of betraying their presence to an alert 
enemy. As a solution to this problem, the lab- 
oratory undertook the development of a sub- 
marine triangulation-listening -ranging [TLR] 
system to provide means for silent determina- 
tion of the range of a target when the subma- 
rine was below periscope or radar depth. 

Essentially, the system consisted of two di- 
rectional hydrophones, positioned as far apart 
as possible on the topside, having power train- 
ing and means for maintaining accurate bear- 
ings on the target, together with appropriate 
mechanisms designed and constructed by the 
Sperry Company for calculating the range au- 
tomatically from bearing information fed in 
by means of synchro repeaters. The accuracies 
required, particularly in measurement of target 
bearing, were such as to involve many months 
of experimental work and the development of 
(1) a highly accurate training system, (2) new 
hydrophones possessing improved directional 
characteristics, and (3) means of automatically 
tracking the target, using the output of a lobe- 
comparison system, or right-left-indication 
[RLI], in order that bearing information might 
be accurate and continuous. A preliminary 
system was tested and proved highly successful. 
As the result of its demonstrated performance, 
the Navy requested experimental equipment to 
be installed on a fleet-type submarine for ap- 
praisal of operation under patrol conditions. 
Later, five engineering models were built by the 
Submarine Signal Company and designated 
Model XJAA sonar equipment. 


12.2.3 WCA-2 Modifications 

Developments in the Pacific war in 1944 
made it necessary to alter the general prosub- 


SONAR SYSTEMS 


201 


marine program in order to give attention to 
means for the detection of torpedoes by sub- 
marines. Following various trials, a modifica- 
tion kit known as the torpedo detection modi- 
fication [TDM] was prepared. Test sets were 
found to be satisfactory and by March 1945 
units were being installed in submarines oper- 
ating in the Pacific. 

With the completion of the investigations 
and sea trials, activity was again applied to the 
original problem of single ping echo ranging. 
Although the problem had been limited initially 
to the improvement of accuracy and reliability 
of range measurements, as a result of the ex- 
perience with underwater telephony and TDM 
it was recognized that the WCA-2 submarine 
sonar gear was capable potentially of improve- 
ment in its established functions, as well as 
the addition of valuable supplementary func- 
tions. Accordingly, the problem of modifying 
the WCA-2 gear was carefully reviewed and it 
was found possible to adapt a functional switch 
through which all system interconnections 
could be made. By means of appropriate modifi- 
cations seven different operations of the equip- 
ment were available: (1) single-ping echo 
ranging by modified modulated pulses, (2) tor- 
pedo detection by supersonic listening, (3) 
mine detection by short-pulse echo ranging, 
(4) underwater telephony, (5) code transmis- 
sion, (6) supersonic listening, (7) system align- 
ing and testing. 

The PPI type of presentation used in this 
modification permitted immediate reading of 
both bearing and range of any target giving a 
distinguishable echo. 

Mine Detection 

Late in 1944, the New London laboratory 
concentrated all efforts on the immediate con- 
struction of 12 mine detection units. While the 
preliminary work was in progress it was real- 
ized that the mine detection equipment and the 
torpedo detection modification [TDM] made 
use of a number of equipment units in common. 
Accordingly, designs were revised to include 
provision for torpedo detection as well as for 
mine detection. Thereafter, the equipment be- 
came known as MATD (mine and torpedo de- 
tection) gqar. A prototype model for trials on a 


submarine was rushed through on high prior- 
ity, and simultaneously, further tests of the 
central fundamental elements were carried out 
from a surface ship. In the winter of 1945, a 
prototype model was installed on a ship and an 
extensive series of trials showed that, in gen- 
eral, the equipment gave the expected operat- 
ing performance. By adding a simple accessory 
unit to the MATD equipment it was found pos- 
sible to provide means whereby all the features 
to be desired in a single-ping echo-ranging sys- 
tem were at once available. Thus amplified, the 
MATD modification appeared to permit the 
WCA-2 equipment to meet adequately all the 
more important services which may be per- 
formed by supersonic apparatus. 


The 692 Sonar 

At the time work was begun on the 692 sonar 
system, the standard systems in use on subma- 
rines were rather limited in scope. Need was 
expressed for a system which would supply in- 
formation comparable to that obtainable with 
a periscope. A complete sonar system was re- 
quired which included means for scanning mine 
fields, self-noise monitoring, torpedo detection, 
location of depth charges, sonic depth finding, 
and underwater communication. 

The equipment designated 692 submarine 
sonar, from the OSRD contract number, was 
designed more to facilitate the investigation of 
sonar requirements than to supply a working 
system. The scope of the development, there- 
fore, was quite broad in regard to component 
features, controls, and adjustments and the 
parts were not completely integrated as they 
would be in standard equipment. 

The original project called for the develop- 
ment of a listening system only, which was to 
be supplemented with a standard surface vessel 
type of echo-ranging equipment operating at 
24 and at 50 kc. Subsequently the project was 
expanded to include the development of a short- 
pulse, high-peak power, echo-ranging equip- 
ment to operate over the range of frequencies 
from 10 to 50 kc. Finally, it was agreed to in- 
clude in the echo-ranging system a PPI for 
mine detection. 


202 


PROSUBMARINE EQUIPMENT 


The completed system, which was delivered 
to the Navy, provided continuous search at 
speeds up to 60 rpm, rapid shifting between 
continuous search and hand training, automatic 
or aided target tracking, and maintenance of 
true bearing. The self noise of the training sys- 
tem was low enough so as not to affect listening. 
The listening system was capable of differen- 
tiating between two targets of the same inten- 
sity 5 degrees or more apart. The usable fre- 
quency range extends from about 200 c to 60 
kc, but the band below 10 kc is used only for 


Division of War Research [UCDWR] as a part 
of the general program for development of new 
antisubmarine sonar equipment as mentioned 
in Chapter 11. However, by the time the 
fundamental research and engineering work 
had culminated in an acceptable scanning sonar 
system, emphasis had shifted from antisubma- 
rine activities to the prosubmarine aspect, espe- 
cially in the Pacific theater where our subma- 
rines were encountering heavily mined areas 
close to the Japanese homeland. QLA had 
earlier demonstrated its ability as a mine de- 



detection listening and not for bearing determi- 
nation because of its poor directivity. 

Although the field trials of the 692 sonar 
were of a limited nature, sufficient data were 
obtained to confirm the above statements on 
performance. No trials were made of the short- 
pulse echo-ranging equipment except to check 
its operation. It is expected that further trials 
will be made by the Navy to obtain additional 
information on the capabilities of the system. 

12.2.5 QLA Sonar for Submarines 

The FM (later designation QLA) sonar proj- 
ect was carried out by University of California, 


tection device in Atlantic and Mediterranean 
tests, and as a result, the Navy requested sev- 
eral systems for submarine installation. 

These systems, although of the same basic de- 
sign as the evaluation models originally de- 
veloped for antisubmarine work, were repack- 
aged and slightly modified with an eye to the 
installation space limitations and the particu- 
lar mine detection applications contemplated 
for submarine use. These considerations led to 
the incorporation of the PPI screen and all 
system controls in a single compact indicator 
unit which could be installed in the already 
crowded conning tower. The bulk of the system 
could then be installed at some remote point in 



SUBMARINE NOISE REDUCTION 


203 


the submarine where space was at a lower 
premium, usually the forward torpedo room. 
Special attention was given to the choice of 
range scales best suited for mine detection and 
plotting. Transducer construction and training 
gear was improved to provide the strength nec- 
essary to withstand the buffeting of heavy seas, 
especially with deck-mounted installations. 

A total of 48 such systems were built, 22 of 
which had been installed on operating subma- 
rines up to the time hostilities with Japan 
ceased. 


XQKA (ER Sonar) System 

Harvard Underwater Sound Laboratory 
[HUSL] developed an electronic scanning sys- 
tem which had scanning speeds of 350 rps. 
This permitted the use of transmitted pulse 
lengths as short as 3 msec and provided excel- 
lent range resolution. The use of short pulses 
is especially advantageous in the detection of 
small reflecting objects, such as mine cases. 
This feature made the ER scanning system 
welcome aboard submarines. Three experimen- 
tal models of this equipment designed for sub- 
marine installations were constructed by 
HUSL under the designation XQKA. The first 
of these models, installed in USS Dolphin at 
New London, indicated a normal detection 
range of 600-1,400 yd for standard mine cases, 
with occasional indications at ranges as great 
as 2,100 yd. The typical discovery range ap- 
peared adequate to permit the submarine com- 
mander to conn his vessel safely through a mine 
field. One of these experimental models was at 
Pearl Harbor for service trials under NRL 
auspices when World War II ended. 


12 3 SUBMARINE NOISE REDUCTION 

In November 1943 a project was initiated to 
study methods for reducing submarine noises, 
develop methods for quantitatively measuring 
submarine under-way or equipment noises, and 
develop standards for noise measurements. De- 
velopment work on equipment for making 
quantitative noise measurements had already 


been completed in 1943. By means of this equip- 
ment, the New London laboratory first under- 
took a comprehensive survey of the magnitude 
and spectral-energy distribution of the subma- 
rine’s auxiliary machinery. 

One of the noisiest auxiliaries was the gyro 
setting regulator which was selected for critical 
analysis. Extensive measurements made of the 
component parts 6f the gyro setting regulator 
indicated practical ways of obtaining noise re- 
duction by the use of improved mountings as 
well as redesigning the equipment. 

Phonograph recordings, noise and vibration 
frequency analyses were made of the noises 
from bow and stern planes, steering, gyro, d-c 
— a-c motor generators and others, oil, drain 
and trim pumps, and other auxiliary machinery 
units in order to determine the most satisfac- 
tory methods of reducing noise. Also noise and 
vibration frequency analyses were made of pro- 
pulsion motors, reduction gears, shaft and 
bearing howls. These measurements were made 
with the submarine at a dock and under way 
using the hydrophones of the OAY sound meas- 
uring equipment at a distance of about 200 ft. 

At the time the studies of sound measuring 
methods were undertaken, such measurements 
were commonly made on the sound range when 
the submarine was either under way or on the 
bottom. Since the measurements on a subma- 
rine under construction obviously could not be 
made on the sound range until it had been 
nearly completed or placed in operation, the 
difficulties of making any necessary adjust- 
ments or structural changes in the short time 
available after the measurements were consid- 
erably increased. 

Therefore an overside technique was devel- 
oped which permitted measurements of auxil- 
iary machinery noise to be made at dockside 
during construction of the submarine, prior to 
sound range tests. This afforded opportunity 
for any necessary modifications at a stage of 
construction when changes could be made more 
readily. 

This method was extended to refit areas 
throughout the United States and advanced 
bases. However, at certain naval activities 
where submarine sound measurements were 
conducted, notably Pearl Harbor, the sound 




204 


PROSUBMARINE EQUIPMENT 


testing and background noise conditions were 
unfavorable for dockside measurements and 
consequently the use of the overside technique 
was impracticable without supplementary 
means for reducing background noise. To solve 
this problem the auxiliary repair dock [ARD] 
was suitably modified by adding an apparatus 
for creating a sound-insulating bubble screen. 
The ARD has become an important adjunct of 
the overside technique because of its mobility 
and availability in forward areas. 


12,31 OAY Sound Measuring Equipment 

After the New London laboratory initiated 
its program for studying methods for reducing 



Figure 4. Model OAY sound measuring equip- 
ment. 


submarine noise and developing methods for 
quantitatively measuring the noises, the first 
step was to develop standardized noise measur- 
ing apparatus. 

The OAY sound measuring equipment was 
developed in 1943 and was adopted by the Bu- 
reau of Ships. This apparatus thereafter 
served as the standard measuring device 
wherever submarine noise measurements were 
made. 

Although field calibrations indicated that the 
equipment was both reliable and sturdy, cer- 
tain improvements were made such as the addi- 
tion of a 1,000-c low-pass (shrimp) filter, and 
facilities for the use of analyzing equipment. 
These and other improvements were incor- 
porated in a redesign of the meter and hydro- 
phone. Between 1942 and 1944, the Bureau of 
Ships' program of submarine noise reduction 
effected an average 20-db drop in noise level. 
The New London laboratory, using OAY sound 


measuring equipment, cooperated in the latter 
stages of this program. 


Noise Level Monitor and 
Cavitation Indicator 

The New London laboratory had developed 
JP-1 sound receiving equipment in 1943, and 
had made it available to the Navy for use on 
patrol. JP-1 equipment revealed merely the ex- 
istence of own-ship’s noises which might be de- 
tected by the enemy, and did not measure the 
noises quantitatively. Observations during ini- 
tial use of the JP-1 listening system brought 
out the need for a system which would enable 
a sound operator to measure accurately the 
noise produced by his own submarine. 

Preliminary monitoring tests were made em- 
ploying the JP-1 equipment as well as DCDI 
(depth charge direction indicator) hydro- 
phones connected to the JP-1 amplifier, but 
these systems were found to be inadequate. A 
modification of the JP-1 system was finally de- 
veloped, and named the noise level monitor 
[NLM]. The NLM, which gives accurate quan- 
titative measurement of own-ship’s noise, uses 
four NL-130 hydrophones and either the JP-2 
or JP-3 amplifier, together with associated 
equipment. 

A cavitation indicator [Cl], installed as part 
of the NLM equipment, gives an indication of 
cavitation produced by the boat’s propellers. 
The Cl employs a fifth hydrophone mounted on 
the submarine pressure hull close to the pro- 
pellers, the red light indicator channel of the 
auxiliary 755 receiver-amplifier, and suitable 
neon glow lamps. The neon lamps, which give 
the cavitation indication, can be located either 
in the conning tower, the forward torpedo 
room, the maneuvering room, or in more than 
one of these places if desired, in order to permit 
quick control of propeller speed and thus avoid 
cavitation. 

The first models were installed on three sub- 
marines and later five more were manufac- 
tured. Construction of 359 units was authorized 
by the Navy and installation was begun in the 
spring of 1945. 


EVASION AIDS 


205 


EVASION AIDS 


12 41 Depth Charge Position Indicators 


In March 1943, the New London laboratory 
began development of a device intended to pro- 
vide a submarine with reliable indications of 
the approximate bearing of exploding depth 
charges. The depth charge direction indicator 
[DCDI] was finally developed which was ca- 
pable of indicating in which quadrant a depth 




¥ 9 ‘9 


• •. • 




& * 


-t — i--. S2 


Figure 5. Amplifier-indicator panel view of 
depth charge direction indicator. 

charge exploded with respect to the submarine 
and whether or not it was above or below the 
boat’s centerline. Initial tests of the first model 
were encouraging and additional, improved 
models were built. These proved satisfactory in 
the quadrant indications, although the above- 
below indications were not always reliable be- 
cause of the water temperature gradients. The 
laboratory oceanographic group subsequently 
devised simple rules for interpretation of 
above-below indications in terms of bathyther- 
mograph traces. 

As now designed, the DCDI employs six mag- 
netostriction hydrophones mounted and con- 
nected so that when subjected to the shock- 
wave from a depth charge explosion, an ampli- 
fier-indicator in the conning tower indicates 
whether the exploding depth charge is forward 
or aft, port or starboard, above or below. 

In the process of developing the DCDI, and 


as submariners visited the laboratory, it be- 
came evident that only half the problem had 
been solved. It was desirable to know not only 
the general direction of the exploding depth 
charge, but also the approximate range. It was 
determined that a rough correlation existed be- 
tween the range of the exploding depth charge 
and the amplitude of the initial pressure im- 
pulse received. Since the initial pressure im- 
pulse is subject to the vagaries of sound trans- 
mission in the ocean, the limits within which 
the range could be determined became the im- 
portant consideration. A practical depth charge 
nange estimator [DCRE] was finally designed 
which is capable of indicating the range of the 
depth charge explosion in the following incre- 
ments: 0-250, 250-500, 500-1,000, and 1,000 yd 
or greater. 

Six development models of the DCRE were 
built, and after tests proved satisfactory opera- 
tion, it was recommended for production. 


Noisemakers and Decoys 

A basic part of the program was the develop- 
ment of sonar countermeasures. Evasion de- 
vices of many types were produced for use by 
submarines and were designed to jam echo 
ranging, to provide false target indications, to 
mask or to confuse sonic and supersonic listen- 
ing, and, in the decoy devices, to simulate sub- 
marine target characteristics. Although no 
single one of these devices was believed to pro- 
vide absolute protection, tactics were developed 
using several different devices in combination 
which significantly enhanced the submarine’s 
chances of escape. 

In the spring of 1943, as the emphasis in 
naval warfare shifted to the Pacific, requests 
were received from submarine commanders for 
devices to neutralize or misdirect enemy detec- 
tion methods. In cooperation with a number of 
the Navy laboratories, Division 6 laboratories 
undertook a countermeasures program. The 
UCDWR laboratory at San Diego had acquired 
a great deal of directly applicable experience in 
developing training devices for antisubmarine 
personnel. The Massachusetts Institute of 
Technology [MIT] laboratory had participated 


206 


PROSUBMARINE EQUIPMENT 


in the development of mechanical noisemakers 
for sweeping acoustic mines. Both groups were 
experienced in the measurement and analysis 
of the ship sounds which were to be masked or 
simulated. 

NAC Sound Beacon 

The first evasion device to be used in combat 
was the NAC sound beacon, designed to jam 
echo ranging. This device, 3 in. in diameter and 
31 in. long, after release from the signal ejector 



Figure 6. The NAC sound beacon. 


of a submarine, radiates from a crystal trans- 
ducer a supersonic signal that sweeps the range 
of frequencies used in echo ranging several 
times a second, thus causing a periodic jam- 
ming signal. The NAC is equipped with a depth 
control which supports it at a depth of 50 ft 
so that it cannot be seen from the surface or 
recovered by the enemy. This device was used 
during the spring and summer of 1945 in com- 
bination with the Navy's FTS (false target 
shell) and NAE noisemaker in submarine eva- 
sion maneuvers. 

XNAG Sound Beacon and Pepper Signal 

Both the XNAG sound beacon and the pepper 
signal were developed by the NDRC laborato- 
ries as noisemakers to mask or disguise subma- 
rine noises from sonic listening detection. The 
characteristic noises produced by a submerged 
fleet-type submarine include a constant-fre- 
quency reduction-gear whine which varies in 
pitch with speed, and an amplitude-modulated 
wide-band noise caused by propeller cavitation 
when running above certain vertical speeds. To 
blanket these noises from detection in any 
region of the spectrum in which the enemy may 
be supposed to be listening, a noisemaker must 
have a high output level throughout the same 


range of frequencies. The XNAG utilizes two 
soundheads; an electromagnetic soundhead is 
driven electronically to sweep through the 
range of low frequencies where gear whines 
occur, while a rotary impactor head produces 
the wide-band output. The high ratio of stored 
energy to volume, which is characteristic of 



Figure 7. Mark 20 pepper signal supported on 
depth control. 

explosive materials, led to the development of 
the explosive noisemaker, pepper signal, which 
has a firing rate of two shots a second. Effec- 
tive performance is obtained in shallow water 
where reverberations maintain a masking level 
of noise between explosions. In deep water, 
however, tests have shown that contact with a 
submarine can be maintained by listening be- 


EVASION AIDS 


207 


tween explosions. The pepper signal develop- 
ment was completed in time for one unit to be 
used in the course of a successful evasion. 

NAD Sound Beacon 

Realistic simulation of actual submarine 
noise and behavior is approximated by the 
NAD sound beacons. These decoys are self- 
propelled, proceeding upon a preset course at 



Figure 8. Loading NAD-3 sound beacon in sig- 
nal ejector. 


pedo tubes rather than from the signal ejector, 
and have operating lives of 30 to 60 minutes. 
The self noise simulation of the NAD-6 is pro- 
vided mechanically by a gear and roller system 
which vibrates the cylindrical housing of the 
beacon, simulating both gear whine and cavita- 
tion noise. In the NAD-10, a cylindrical mag- 
netostriction loudspeaker is driven by an elec- 
tronic signal which is made up of an amplitude- 
modulated wide-band noise and a constant-fre- 
quency whine. The echo repeaters in these two 
decoys are adjusted so that any ping striking 
the receiver hydrophone is retransmitted at a 
level equivalent in strength to the echo from a 
full-size submarine. The smaller NAD-3, which 
can be ejected from the signal tube, provides 
simulation of self noise only. NAD maintenance 
shops and training schools were set up at San 
Diego and Pearl Harbor during the spring of 
1945, and one NAD-6 was used in a successful 
evasion maneuver. 

12 - 4 ' 3 Other Aids 

Many other schemes were investigated for 
jamming, masking, and decoying. Although 



Figure 9. NAD-6 sound beacon assembly and subassemblies. 


preset depth and emitting noise similar in 
character to submarine self noise while return- 
ing echoes with doppler to echo ranging. The 
NAD-6 and the NAD-10 are released from tor- 


those devices accepted by the Navy proved use- 
ful, their many limitations show that the art 
is still in its infancy. In the continuing Navy 
programs, attention is being directed to the re- 




208 


PROSUBMARINE EQUIPMENT 


finement of many of these devices. The NAH, 
using a self-tuning mechanism to keep the radi- 
ated jamming signal automatically at the exact 
echo-ranging frequency in use by the enemy 
search vessels, is expected to replace the NAC. 
New, compact fuel sources give promise of in- 
creasing the efficiency of sonic noisemakers. 



Figure 10. The NAD-10 sound beacon. 

The development of depth controls, which was 
an important part of the development of these 
expendable devices, is also continuing. 

A somewhat different approach to the prob- 
lem of neutralizing enemy detection methods 
was in the development of an acoustic absorb- 
ing coating, to be applied like paint to the ex- 
terior of the submarine. Calculations indicate 
that such a material, if it produced an absorp- 
tion of 10 db throughout the echo-ranging fre- 
quencies would so reduce the effectiveness of 
echo-ranging detection, that in many oceano- 
graphic conditions it would become altogether 
useless. Both German and Japanese laborato- 
ries were carrying on similar developments at 
the close of World War II. In the coating under 
development in the NDRC laboratory at MIT, 
the active part consists of a number of layers 
of synthetic rubber in which small air bubbles 
are trapped. This coating appears to be prac- 
tical. It provides absorption of 10 db at its 
optimum temperature and pressure and its 
absorption is independent of frequency be- 
tween 10 and 30 kc. The work continuing on 


this program is directed towards increasing 
control of the pressure and temperature de- 
pendence of the coatings, and making funda- 
mental studies of the absorption mechanism to 
permit better evaluation of its operational per- 
formance. 

The future development of submarine eva- 
sion devices will depend upon the development 
of new subsurface detection techniques both in 
the field of listening and echo-ranging gear, 
and on the development of guided ordnance. A 
new NAD might be designed to represent a sub- 
marine for wake detection, magnetic detection, 
optical detection, and so forth, as well as for 
listening and echo-ranging methods. It might 
also be equipped to execute maneuvers, diving, 



Figure 11. NAD-10A sound beacon partially 
loaded in a torpedo tube. 


and changing course during a protracted life 
to increase its resemblance to a submarine. On 
the other hand, the general concept of false 
targets might be extended, to provide false 
wakes, false optical targets, or false propeller 
sounds. The emphasis on homing ordnance for 
use against submarines calls for immediate at- 
tention to this type of problem. 



Chapter 13 

ACOUSTIC TORPEDOES 

By Eric Walker 


13 1 INTRODUCTION 

B Y the time of the first World War the tor- 
pedo had reached such a stage of develop- 
ment that it was used both by surface vessels 
and by submarines. Ever since the proposal by 
Whitehead in 1866, study had been made of 
methods for controlling and directing a torpedo 
toward a target. Many methods for remote con- 
trol were suggested and some were tried. One 
of these schemes, which achieved functional if 
not operational success before 1925, used long- 
wave radio signals which could be received by 
the torpedo when it was running at shallow 
depth. None of the control methods tried before 
World War II, however, seemed to meet mili- 
tary requirements. 

The idea of acoustical tropistics, that is, the 
use of sound waves to influence a missile to 
home on its target, was frequently reinvented 
after 1918. In spite of the attractiveness of 
applying such homing control to a torpedo, the 
scheme had always been judged to be imprac- 
tical because the torpedo was so noisy. It is in 
fact difficult to imagine a less promising loca- 
tion for a sensitive hydrophone than a position 
close to a compact, high-speed steam turbine de- 
livering more than 100 horsepower through 
brass gears to two small propellers threshing 
the water in opposite directions. 

Despite this discouraging prospect, British 
scientists, prior to the entry of the United 
States into World War II, undertook experi- 
ments to determine just how noisy a torpedo 
was. On the basis of these noise studies the 
British developed a satisfactory echo-ranging 
acoustic torpedo. The Germans also experi- 
mented with various types of control and de- 
veloped several models of acoustic torpedoes. 
The Italians, too, developed a listening acoustic 
torpedo, but of questionable effectiveness. 

In the United States all consideration of 
acoustic homing control had been pointed 
toward its application to full-scale, high-speed 
torpedoes of the type used in surface warfare. 
However, the self noise of high-speed torpedoes 


prevented the application of practical acousti- 
cal control. In the fall of 1941, the Navy pro- 
posed the application of acoustical control to a 
small, slow-speed torpedo, and requested the 
NDRC to set up a research and development 
program. This program, identified as Project 
61, was distributed among several groups and 
resulted in the development and production of 
a successful aircraft-launched acoustic listen- 
ing torpedo which played an important part in 
underwater warfare against enemy submarines. 

Success in application of acoustical homing 
control in Project 61 naturally revived interest 
in extension of such control to full-scale, high- 
speed torpedoes. For this purpose three new 
development programs were undertaken, begin- 
ning in the spring of 1943. One of these, Project 
NO-149, was intended to provide acoustical 
homing control for air-launched torpedoes to 
be used against surface craft. Another, Project 
NO-157, was intended to lead to application of 
similar acoustical homing control to an electric 
torpedo for use by submarines against surface 
craft. Development of echo-ranging control for 
torpedoes to be launched from surface craft 
against submarines was conducted under Proj- 
ect NO-181. 

In order to start Project NO-157 as quickly 
as possible, the Mark 18, an electric torpedo 
with a speed of 29 knots, was selected as an 
experimental vehicle and it served in this way 
throughout the remainder of the program. From 
the Mark 18 were developed three acoustically 
controlled torpedoes, designated Mark 28 (20 
knots), Mark 29 (25 knots), and Mark 31 (28 
knots). Also, the Mark 20, a high-speed (39 
knots) electrically powered antisurface ship 
torpedo was provided with acoustical control. 

In a similar way, the steam-driven 33-knot 
Mark 13 aircraft torpedo served as the experi- 
mental vehicle for development of an air- 
launched acoustic torpedo for use against sur- 
face ships, under Project NO-149. The acoustic 
version was designated as the Mark 21. 

The small antisubmarine mine (which in its 
acoustic version was the Mark 24), served as 


209 


210 


ACOUSTIC TORPEDOES 


an experimental vehicle in Project NO-181 for 
development of a ship-launched antisubmarine 
torpedo with echo-ranging homing control. The 
final model was designated Mark 32. Later, 
echo-ranging control was also applied to the 
29-knot Mark 18 ship-launched antisubmarine 
torpedo. 

Many of the basic development problems en- 
countered were common to all three projects 
and the various aspects of the problems were 
pursued with whichever torpedo body seemed 
best adapted for the purpose. The major part 
of the effort was directed toward studies of 
torpedo self noise, improved hydrophones, and 
electronic control systems. Studies and tests 
were made to eliminate self noise by developing 
vibration- and noise-isolating techniques and 
developing quieter power systems. The pro- 
gram also included tests and studies of stability 
and control, buoyancy, batteries, motors, and 
propellers. 

The self noise of the torpedoes was reduced 
by improving the directivity of the hydro- 
phones, by reducing noise and vibration by 
isolating various components of the torpedo, 
and by elimination of sources of waterborne 
noise at the torpedo tail by improving propeller 
design and by isolating reversing gear supports 
from the shell of the torpedo tail. 

An electronic control system was designed to 
furnish improved stability and ease of main- 
tenance. This system was called the pilot panel 
because it used an auxiliary pilot signal to sta- 
bilize the amplification of the different hydro- 
phone channels. The electronic control system, 
improved hydrophones, and isolating tech- 
niques, made it possible to furnish manufac- 
turing designs meeting the specifications set up 
under the three projects. 

Although the prototypes of the Mark 21 and 
Mark 31 performed in accordance with their 
specifications, neither was manufactured in 
quantity for operational use before the end of 
World War II. In July 1945, limited production 
of these two models was begun at Forest Park 
and the Newport Torpedo Station in order to 
continue field tests. 

While the Mark 21 and Mark 31 were being 
developed, BTL and HUSL designed and devel- 
oped the Mark 28. Some of these torpedoes, 


manufactured by Western Electric Company, 
reached the Pacific in time for service trials 
before the end of World War II. 

The Mark 29, successor to the Mark 28, incor- 
porated all the improvements as they became 
available from the basic research program. The 
Mark 29 used counterrotating propellers 
driven by a newly developed counterrotating 
motor. It included most of the vibration-isolat- 
ing features developed previously. Preliminary 
models were completed and tested but the mod- 
els were lost during the trials and the program 
had to be terminated before it was possible to 
determine the relative merits of the Mark 31 
and Mark 29 designs. 

The echo-ranging model of the antisubma- 
rine mine, Mark 32, was completed by Leeds 
and Northrup, and tests conducted in 1944 
yielded reasonably satisfactory results. No field 
trials were conducted with the echo-ranging 
model of the Mark 18. The final experiments 
under the NDRC program were with the Mark 
20 which, in tests, produced self-noise levels at 
37 knots comparable to the Mark 31 at 28 knots. 
The Mark 20 had excellent acoustical steering 
in both azimuth and depth. 


132 PROJECT 61 

In 1941, the Navy proposed that NDRC set 
up a research and development program to 
design a slow-speed torpedo which could be 
launched from aircraft for use against subma- 
rines and which would be quiet enough to per- 
mit application of acoustical homing control. 
The development program (NO-94, later Proj- 
ect 61) was assigned to Harvard University 
Underwater Sound Laboratory [HUSL], the 
Bell Telephone Laboratories [BTL], the Gen- 
eral Electric Company [GE], and the Columbia 
University Special Studies Group [CUSSG]. 

A speed of 12 knots was suggested since this 
would be sufficient to overtake the fastest sub- 
merged submarine then operating and acous- 
tical control could be more easily applied to a 
weapon of this slow speed than to a standard 
(noisy) high-speed torpedo. As the acoustical 
control would lead the antisubmarine torpedo 
into direct contact with its target, a relatively 


PROJECT 61 


211 


small explosive charge would be sufficient to 
inflict lethal damage. Therefore, development 
of a device was undertaken to meet the follow- 
ing tentative specifications. 

1. Propulsion : electric, single-rotating motor. 

2. Power source : lead storage battery. 

3. Speed : 12 knots. 

4. Duration of run : 5 to 15 minutes. 

5. Explosive charge: 100 lb. 

6. Dimensions: 84 in. long and 21 in. diam- 
eter. 

7. Type of directional control : acoustical. 


Basin designed a propeller to meet estimated 
thrust requirements. 

BTL and HUSL Systems 

Several parallel lines of attack on the hydro- 
phone problem were followed. BTL proposed 
the use of crystal hydrophones mounted in the 
cylindrical body section of the torpedo, while 
HUSL explored the use of magnetostriction 
hydrophones mounted on the nose. The only 
important differences between the BTL and 
HUSL systems were the location of the hydro- 


Table 1 . NDRC torpedo development program (acoustically controlled torpedoes). 


Original model 
designation 

Description 

Project 

number 

Acoustic control 
specifications 

Final acoustic 
model designation 

Antisubmarine 

mine 

Small-sized, stubby, 
electrically 
powered; 12 knots 

(NO-94) 
(Fido) 
project 61 

Air-launched, antisubmarine; 
acoustic homing control 

Mark 24* 

Mark 27* (revamped 
Mark 24) 

Mark 18 

Antisurface ship, 
electrically 
powered; 29 knots 

NO-157 

Submarine-launched, antisurface 
ship ; acoustic homing control 

Mark 28 (20 knots) f 
Mark 29 (25 knots) 
Mark 31 (28 knots) 

Mark 20 

Antisurface ship, 
electrically 
powered; 39 knots 

NO-157 

Submarine-launched, antisurface 
ship ; acoustic homing control 

Mark 20 (37 knots) 

Mark 13 

Antisurface ship, 
steam driven; 33 
knots 

NO-149 

Air-launched, antisurface ship; 
acoustic homing control 

Mark 21 (33 knots) 

Antisubmarine 

mine 

Small-sized, stubby, 
electrically 
powered; 12 knots 

NO-181 

Ship-launched, antisubmarine ; 
echo-ranging homing control 

Mark 32 (12 knots) 
(also air-launched) 

Mark 18 

Antisurface ship, 
electrically 
powered; 29 knots 

NO-181 

Submarine-launched, antisurface 
ship; echo-ranging homing 
control 

Mark 18, echo-ranging 
model. (Untested) 


* Used successfully in World War II combat, 
t Combat performance record classified. 


8. Launching .method : from aircraft making 
125 knots at 250 ft. 

9. Acoustic range : as great as possible. 

For security reasons during development 

work, the device was called a mine rather than 
a torpedo. Four teams were organized and de- 
velopment got under way in December 1941. 
GE was assigned responsibility for the design 
of a propulsion motor and various control 
features. The HUSL and BTL groups were 
responsible for development of suitable hydro- 
phones and electronic mechanisms for provid- 
ing acoustical control. The David Taylor Model 


phones and the material of which they were 
made. The method of operation was the same. 

In the BTL system, steering was accom- 
plished by mounting four hydrophones sym- 
metrically around the axis of the body, two 
for vertical control and two for horizontal con- 
trol. Arranging the hydrophones in pairs for 
up-and-down and right-and-left directional con- 
trol made it possible for the mine to steer 
always toward the location of the noise source 
regardless of how the highly maneuverable 
body might roll or twist in attacking and re- 
attacking. 


212 


ACOUSTIC TORPEDOES 


A depth control was designed so that in the 
absence of any signal from the target the mine 
would cruise at a depth of 45 ft. Rudder areas 
were sufficient to produce a turning circle of 
small radius (35 ft). In the absence of target 
signal, the combination of proportional rudder 
response and small unavoidable unbalance in 
the hydrophones, amplifier channels, and re- 


eventually replaced by an electronic switching 
arrangement. 

Effort was devoted during 1942 to problems 
arising from air launching of the device. A 
strengthened body was constructed to permit 
drop tests of the electronic components and 
control equipment. Information was thus ob- 
tained concerning the methods of constructing 



Figure 1 . Project NO-157, submarine-launched listening torpedo. 


ceived self noise usually produced rudder posi- 
tions which caused the body to execute a satis- 
factory searching circle about 50 yd in diam- 
eter. 

Early systems utilized a comparison ampli- 
fier which employed a mechanical commutator 
allowing a single amplifier channel to be used 
alternately for right-and-left or up-and-down 
steering. This mechanical commutator was 


and mounting the equipment to withstand the 
shock occurring at water impact. 

The Mark 24 

The final production model selected was based 
on many of the features developed by BTL in- 
cluding the provision of crystal hydrophones 
mounted symmetrically on the body. Further 
tests were carried out during 1943 and 1944 



PROJECT NO-157 


to investigate the behavior of the production 
model of the Mark 24 under special operating 
conditions. Particular attention was given to 
adjustments permitting the mine to attack deep 
submarines. Successful attacks were carried 
out on artificial targets at depths of 435 ft 
and preliminary tests have indicated that the 
limiting depth of the body is about 600 ft. In 
order to facilitate deep attacks, a standard 
running depth of 150 ft was recommended and 
corresponding changes were made in the mines 
already in the operating theaters. 

The Mark 27 

Later, a longer torpedo body was used and 
this revamped Mark 24 developed by BTL was 
designated Mark 27. The Mark 27 was intended 
to be a protective device to be used defensively 
against attacking enemy submarines. However, 
skippers found that it was also an effective offen- 
sive weapon. The Mark 24 and Mark 27 were the 
only acoustic torpedoes used extensively during 
World War II and a record of their results 
shows that they were an important factor in 
controlling and eliminating the U-boat menace. 


133 PROJECT NO-157 

This project, concerned with the application 
of acoustical homing control to an electric tor- 
pedo for use by submarines against surface 
craft, resulted in the designing of four models, 
the Mark 28, Mark 29, Mark 31, and the Mark 
20 (37-knot acoustic version). Each of these 
four models met the specifications of the proj- 
ect. However, the Mark 31 and the Mark 20 
were the most successful in field tests, and 
further development work on these models is 
continuing. 

During the successful field trials of produc- 
tion units of the low-speed acoustic antisub- 
marine mine, the Mark 24, engineers became 
eager to experiment with the application of 
similar acoustical control methods to a full-size 
high-speed torpedo. In April 1943, two units of 
the electric torpedo Mark 18 were made avail- 
able to HUSL for experimentation. The first 
problems tackled were those of installing hy- 
drophones in the nose of the empty warhead 


213. 


and providing amplifiers and recording equip- 
ment for measuring the self noise of the tor- 
pedo under operating conditions. The first 
trials revealed that at the high speed of 29 
knots this torpedo was indeed very noisy. Con- 
sequently, adjustments were made to provide 
for lower operating speed. 

The sound fields produced at various dis- 
tances by various warcraft were studied and 
target specifications were established. For a 
20- or 25-knot torpedo to be effective it should 
be susceptible to the sound levels produced at 
a range of at least 200 yd by a destroyer or 
cruiser operating at 15 knots, or by a merchant 
vessel operating at 8 to 12 knots. Studies indi- 
cated that acoustical control on a sound field 
of the order of —39 db spectrum level (db vs 
1 dyne per sq cm for 1-c bandwidth) would 
be required to provide a useful tactical range 
for the acoustic torpedo. Early trials indicated 
that the Mark 18 electric torpedo would not 
meet this specification at its full operating 
speed. 

The development program was accordingly 
subdivided so that the three overlapping as- 
pects of the problem might be attacked simul- 
taneously. They were: 

1. Continuation of the program of torpedo 
self-noise measurements and analysis. 

2. Development of hydrophones to have im- 
proved discrimination against self noise orig- 
inating near the stern of the torpedo. 

3. Experimentation with methods of quieting 
the reversing gears. 

The program of noise measurements led to 
improved understanding of the role played by 
cavitation at the torpedo propellers and also 
revealed that even in the absence of cavitation 
there were enough other sources of self noise to 
justify the long-held skepticism of the feasi- 
bility of acoustical control for high-speed tor- 
pedoes. 

However, it has been found that good noise- 
reducing results could be obtained by a simple 
modification of the standard Mark 18 torpedo 
tail, namely, the vibrational isolation of the 
three-pronged spider which carries the revers- 
ing idler gears. Also the nose section, carrying 
the hydrophones, was isolated by a gasket ar- 
ranged to avoid any metal-to-metal contact and 


214 


ACOUSTIC TORPEDOES 


the directivity of the hydrophones was im- 
proved. 

Another opportunity to introduce vibrational 
isolation in the noise transmission path was 
afforded by the mounting of the hydrophone 
itself. The hydrophone mounting problem re- 
ceived intensive study aided by a long series 
of measurements. Continued hydrophone re- 
search had led to design of a unit having such 
improved directivity that under favorable con- 
ditions there was as much as 35 to 50 db dis- 
crimination between sounds arriving along the 
axis of the hydrophone and sounds arriving 
from the rear along the axis of the torpedo 
body. 

Combining the results of these various stud- 
ies, it appeared possible in late 1944 to assem- 
ble a modified Mark 18 torpedo containing iso- 
lated idler gears, vibration-isolating gaskets 
between the body and the nose, and a group of 
four isolated hydrophones mounted in the nose 
section. 

The combination of these modifications to- 
gether with a new four-channel comparison 
amplifier (utilizing pilot signal method) yielded 
an acoustic torpedo that operated on specified 
sound levels at a speed of 28 knots. 

The Mark 28 

During the development program, the HUSL 
and BTL groups obtained sufficiently optimistic 
indications to suggest that it would be feasible 
to undertake commercial production of an 
acoustic torpedo that would operate at 20 knots 
with a single propeller, thus eliminating gear 
noise. The device was frozen for production 
purposes at the prevailing stage of develop- 
ments, and Westinghouse Electric Corporation 
[WE] was assigned to design and manufacture 
the torpedo designated Mark 28. Acoustical 
control equipment was produced by the Western 
Electric Company. 

The Mark 29 

As the research program continued, designs 
by BTL and WE began to take shape for a 
25-knot successor to the Mark 28, designated 
Mark 29. Among the new features introduced 
in the research program for the Mark 29 was 
the use of a counterrotating electric motor 


which could be coupled with two propellers 
without the use of noisy reversing gears. 
Though an improvement from the standpoint 
of noise reduction, this arrangement failed to 
achieve either the weight reduction expected, 
or the advantage of automatically balanced 
torque. 

Several hundred Mark 28’s were manufac- 
tured and delivered to the Navy. Three experi- 
mental Mark 29’s were constructed, but were 
lost during initial trials before their acoustical 
behavior could be tested. 

The Mark 31 

As mentioned previously, when the Mark 18 
was equipped with modifications for self-noise 
reduction and increased directivity, it dis- 
played satisfactory acoustical control at 28 
knots. Such modification of the Mark 18 was 
given the designation Mark 31 and an experi- 
mental lot was manufactured. Performance of 
the Mark 31 in reasonable accordance with the 
design objectives was obtained in trials at 
Solomons, Maryland. However, the ordnance 
development program was transferred from 
HUSL to the Ordnance Research laboratory at 
the Pennsylvania State College and took place 
before tests had been made to establish the 
relative merits of the Mark 29 and the Mark 31. 
Future development work might be directed to 
combining the inherent advantages of the 
counterrotating motor of the Mark 29 with 
other desirable features of the Mark 31. 

The Mark 20 

Early in World War II, GE had developed a 
high-speed motor with reducing gears for tor- 
pedo propulsion. This relatively lightweight 
motor was incorporated in the Navy’s Mark 20 
torpedo which was expected to operate at 39 
knots with a primary battery. A new sphero- 
give head was designed for the Mark 20 and 
four of the latest 12-tube magnetostriction hy- 
drophones, shown in Figure 2, were fitted 
in forward-looking, downward-tilted internal 
mounts. With this new head, the recorded self- 
noise level of the Mark 20 at 37 knots appeared 
to be even lower than that of the Mark 31 at 
28 knots. The acceptability of this noise level 
was confirmed by reconnecting, as a steering 


PROJECT NO-149 


215 


amplifier, the pilot channel amplifier used for 
noise measurements and conducting steering 
trials. Acoustic steering with this torpedo at 
37 knots was obtained in two runs (one in azi- 
muth and one in azimuth and depth) in October 
1945. 


13 4 PROJECT NO-149 

Project NO-149, to provide acoustical hom- 
ing control for air-launched torpedoes to be used 
against surface craft, resulted in development 



Figure 2. An exploded view of the 12-tube 
magnetostriction hydrophone and an internal 
view of four similar hydrophones mounted in a 
torpedo nose. 

of the Mark 21 steam-driven torpedo which met 
the original specifications. Experiments are in 
progress, however, to improve further the 
acoustic performance. 

While HUSL was working on the acoustical 
development of the Mark 18 torpedo, two 33-knot 
Mark 13 steam-propelled aircraft torpedoes were 
received to serve as interim vehicles for ex- 
periments leading to design of an acoustic air- 
craft torpedo. It was soon apparent that very 
drastic steps would be required if acoustical 
control of the noisy device was to be achieved. 

Hydrophones and noise-recording equipment 


were built into the empty warheads and noise 
tests were conducted. It was concluded that in 
order to permit satisfactory acoustical control, 
all noise from the turbine would have to be 
suppressed until it was at least as low as that 
generated by the propellers and the passage of 
the body through the water.' 

Methods were worked out for operating the 
Mark 13 at speeds as low as 18 to 20 knots, but 
although the self noise became more nearly ac- 
ceptable at these speeds, this low speed was 
not tactically useful against fast surface craft. 
Still other modifications were needed. Because 
the device was to be air-launched, the domes 
had to be built up in order to protect the elec- 
tronic gear. 

The Mark 21 

Continuous noise-reduction tests proved dis- 
couraging, and just as the project was about 
to be abandoned in the spring of 1944, the 
engineer in charge of the noise-reduction pro- 
gram was given permission to make six addi- 
tional runs. Disregarding the scientific princi- 
ple of changing only one variable at a time, he 
undertook to do everything possible to quiet 
the device. 

These changes included isolating mounts for 
the hydrophones, vibration-isolating gaskets to 
support the bulkhead which carried the turbine 
and the propeller-reversing gears, and wrap- 
pings of acoustic insulating material for all 
interior conduits and piping. (See Figure 3.) 
During the next run, the observed self noise 
was very much lower than had been observed 
previously, and repeated trials demonstrated 
that a profound change had been introduced. 

Further studies indicated that vibrational 
isolation of the engine bulkhead was the prin- 
cipal quieting feature. Careful study was then 
devoted to methods by which this isolation 
could be carried out without interfering with 
the droppability of the torpedo. Fairprene, a 
laminated canvas impregnated and faced with 
neoprene, was found to be by far the best gas- 
ket material of those tested. In addition to 
isolating the engine bulkhead and the hydro- 
phones, vibration-isolating joint rings were in- 
stalled between the nose and the center section. 
Thus, three breaks were introduced in the path 


216 


ACOUSTIC TORPEDOES 


leading from the turbine to the hydrophones. 
These relatively simple changes, in conjunction 
with the improved directivity provided by 12- 
tube magnetostriction hydrophones, produced a 
33-knot torpedo with self noise of approxi- 
mately —41 db spectrum level. This perform- 
ance was sufficient to provide a tactically useful 
range on a 15-knot destroyer. During develop- 
ment it was not possible to conduct theoretical 
studies on vibrational isolating materials. Since 


bilization of the gain of individual channels of 
the amplifier; the other, identified as the quad- 
rature system, was based on an amplifier de- 
velopment made in Project NO-181. The quad- 
rature amplifier required fewer tubes and se- 
lective circuits than the pilot channel amplifier, 
but the latter appeared likely to require less 
field maintenance and to impose less stringent 
requirements on the precise adjustment of 
band-pass filters. Although both amplifiers per- 



Figure 3. Exploded vibrational isolation for self-noise control showing (left) the vibrational isolation 
of the high-speed steam turbine, (center) the vibration-isolating forward joint ring with a bayonet lock 
joint for easy access to the control equipment in the nose, and (right) the vibration-isolatecf hydrophone 
mounting. • 


the minimum amount of Fairprene to give max- 
imum isolation efficiency is still unknown, addi- 
tional studies should be made of this problem. 

Before the experimental units of the Mark 21 
were recommended for manufacture, it seemed 
advisable to design a new four-channel com- 
parison amplifier which might incorporate ad- 
vances in technique made since the rather hur- 
ried design of the control panel for the Mark 24 
antisubmarine mine. Two plans were advanced. 
One utilized the pilot signal technique for sta- 


formed satisfactorily, the pilot signal unit was 
selected for manufacture. 

In working out the control features of the 
Mark 21 torpedo it was necessary to provide 
for transmission of electrical control signals 
from acoustical equipment in the nose to the 
air-operated steering engine in the tail. Modi- 
fications were necessary in order to adapt the 
diving mechanism to electrical control. Ar- 
rangements had to be made to superimpose 
the electrical control upon the action of the 


PROJECT NO-149 


217 



AZIMUTH RELAYS 
DEPTH SOLENOID 
FAIRPRENE ISOLATION 


CABLE TUBE 
WATER CONNECTOR 


FAIRPRENE 

ISOLATION 


HYDROPHONES 


B BATTERY 
,A BATTERY 
CONTROL PANEL 


CONTROL CABLE 


Ficure 4. Phantom cross section of a prototype of the steam-propelled air-launched acoustic torpedo, 



Figure 5. Project NO-181, echo-ranging antisubmarine mine. 




218 


ACOUSTIC TORPEDOES 


depth-control mechanism as well as upon the 
mechanism by which steering information is 
normally derived from the gyroscope. It was 
found possible to introduce an elastic link in 
the latter mechanism in such a way that a small 
electric solenoid could override the gyroscope 
information without imposing additional load 
on the gyroscope. This made it possible for the 
torpedo to be launched under normal gyroscopic 
control, with the electrical circuits taking over 
control after a certain time interval or when- 
ever a suitable control signal became available. 

The plan of acoustical depth control selected 
for the Mark 21 (and Mark 31) called for nor- 
mal operation at a depth of 50 ft. The azimuth- 
steering channel was made more sensitive than 
the depth-control channel so that the first tar- 
get signals would be received on the azimuth 
channel alone and would override the gyro- 
scopic control and steer the torpedo in the di- 
rection of the noise source. As the torpedo 
approached the target, the increased signal 
strength would affect the depth-control channel 
and cause up-steering which, in turn, would 
cause a lockout relay to operate, eliminating 
any further influence of the gyroscope on the 
torpedo trajectory. If the torpedo failed to make 
contact on its first pass at the target, the azi- 
muth-control channel would remain locked in 
the direction from which the last signal came, 
causing the torpedo to circle and again pick up 
the target noise. Re-attacks would thus occur 
until the target was hit or until the torpedo ran 
out of fuel. 

Some difficulty was encountered with broach- 
ing when the torpedo was drawn to the surface 
at too steep an angle. Broaching is undesirable 
not only because it may reveal the presence of 
the torpedo but also because the shock at re- 
entry into the water may cause premature op- 
eration of the exploder mechanism, and because 
the torpedo may lose speed by porpoising in the 
target’s wake on a stern chase. To avoid these 
difficulties a climb-angle limiter was introduced 
which prevented the torpedo from climbing at 
so sharp an angle that it could not turn down- 
ward again without breaking the water surface. 

Previous experience in air-launching the 
Mark 24 proved valuable in dealing with the 
aircraft launching problems of the Mark 21. 


In almost all details, the designs for the Mark 
21 components proposed for the production 
model proved to be droppable without alteration. 

In June 1945, full-scale tests were conducted 
at Fort Lauderdale. These tests involved air 
launching against both stationary and towed 
artificial targets and launchings from a PT 
boat against a destroyer. Several hits were 
scored during the tests. Although the homing 
behavior was moderately good, the trials re- 
vealed that the increased turning radius result- 
ing from the addition of a shroud ring at the 
tail had reduced the torpedo’s maneuverability 
for last-moment course corrections. Experi- 
ments on methods to decrease the turning ra- 
dius were in progress when the war terminated. 
Further development is being continued by the 
Ordnance Research Laboratory. 

13 5 PROJECT NO-181 

Project NO-181 called for the development of 
an echo-ranging control for torpedoes launched 
from surface craft against submarines and re- 
sulted in the development of the 12-knot Mark 
32 and an echo-ranging version of the Mark 18 
which operated at 29 knots. Both HUSL and 
GE worked on the Mark 32 development. 

Early in the development program for the 
Project 61 antisubmarine mine (Mark 24), an 
alternative proposal was made to equip such a 
missile to home on its target by echo-ranging 
methods. It was suggested that the most satis- 
factory solution of the surface vessel conning 
problem might lie in the use of a self-propelled 
depth charge which would home on the target 
submarine by echo ranging. Such a mine could 
be launched from a surface vessel and, using 
the attacking vessel’s sonar information, could 
then take up the attack where the surface vessel 
left off, thereby simplifying the conning prob- 
lem. In the spring of 1942 a group of GE 
engineers was assigned to develop such an echo- 
ranging antisubmarine mine and late in the 
same year HUSL engineers began studying 
echo-ranging methods. 

The Mark 32 Mine (GE System) 

In developing the GE echo-ranging control 
system, computations were made which indi- 


FUTURE INVESTIGATIONS 


219 


cated that a simple tactic would protect the 
launching vessel and lead to an almost certain 
attack on the target. According to this plan 
the self-propelled body would be arranged to 
glide downward at a small fixed angle while 
steering tight circles and pinging as it went. 
With a reasonable assumed range of echo de- 
tection, the speed of the mine body was such 
that the target could be intercepted before it 
had escaped from the vicinity of the launching 
point even if it were operating initially at a 
depth as great as 400 ft. Submarine operating 
depths greater than 400 ft and higher subma- 
rine speeds reduce the certainty of such inter- 
ception but a favorable balance can be restored 
by increasing the speed and rate of descent of 
the homing depth charge or by increasing the 
missile’s echo-detection range. 

Besides offering these attractive tactical pos- 
sibilities for use by surface vessels, the pro- 
posed weapon seemed equally likely to be useful 
as an air-launched antisubmarine device. Since 
it would retain its effectiveness in the face of 
noisemakers which would decoy a listening tor- 
pedo such as the Mark 24, its development was 
undertaken on high-priority basis. 

The Modified Mark 18 (HUSL System) 

A systematic study was made of echo-rang- 
ing methods which might be employed. Devel- 
opment work was begun at HUSL on a high- 
frequency (60 kc) magnetostriction transducer 
capable of handling considerable electrical 
power and which would withstand air launch- 
ing (see Figure 5) when mounted in the nose 
of a torpedo body. Then, an echo-ranging trans- 
mitter and receiver as shown in Figure 6 had 
to be designed to fit into a space not much 
greater than that previously occupied by the 
comparison amplifier of the listening Mark 24. 

In one HUSL version, gating arrangements 
were incorporated in the rudder-control cir- 
cuits which blocked all signals except those 
which met predetermined specifications of pulse 
duration, amplitude, and frequency shift. The 
requirement that an echo have target doppler 
in order to qualify for control insured that the 
torpedo would home only on moving targets 
and would ignore artificial bubble targets or 
other echo-producing decoys. 


The transducer program produced a unit des- 
ignated SPEP which seemed entirely satisfac- 
tory at the dropping speeds specified for the 
project. 

An extensive series of field tests were con- 
ducted with the Mark 32 in 1944. The most no- 
table shortcoming in the behavior of the HUSL 
Mark 32 was its operation at ranges less than 
50 ft, where the loss of signals occasionally led 
to glancing impact with the target or to a turn- 
away just before impact. Although it was be- 
lieved that this behavior could be remedied by 
circuit modifications, the anticipated military 
need for an echo-ranging successor to the 
Mark 24 was so great that manufacture was 
initiated on the basis of the simpler GE form 
of echo-ranging control. 

Construction of the improved electronic 
equipment for the HUSL device was completed 
in 1945 and plans were made to install it in a 
full-size Mark 18 torpedo which would provide 
enough space and buoyancy for the equipment 
to record all the principal performance factors. 
No field trials had been conducted when the 
program was transferred to the Ordnance Re- 
search Laboratory. 

13 6 FUTURE INVESTIGATIONS 

In retrospect, there appears to be a wide gap 
between the skepticism with which acoustical 
control for a slow torpedo was undertaken in 
1941 and the acceptance of a successful high- 
speed torpedo in 1945. However, there has been 
very little advance in the design of the targets 
throughout this period, and indeed throughout 
the period between the two wars. Although, the 
Germans made considerable advances in subma- 
rine design, the submarines that saw service in 
World War II were not much faster than those 
of the first World War ; neither were they much 
heavier, nor much more highly armored, nor 
did they carry more potent weapons. 

The advent of the atomic bomb may radically 
change this situation, and much of the scientific 
talent which has been occupied with weapons 
and detection equipment for air warfare may 
be devoted to instruments for underwater war- 
fare. Perhaps it is too early to forecast the 
effect of atomic power on underwater warfare, 


220 


ACOUSTIC TORPEDOES 


at least in so far as such sources of power will 
be used for propulsion or destruction. But the 
fact that torpedoes can be constructed with 
atomic explosive warheads has already been 
demonstrated almost beyond reasonable doubt. 


as rockets or jets, should not be neglected. 
Meanwhile, hydrogen peroxide as part of the 
combustion mixture is already in use. 

No matter what happens, it seems that weap- 
ons of stealth, such as the submarine and tor- 



Figure 6. Control chassis, for the echo-ranging mine, containing a complete echo-ranging transmitter 
and receiver. 


Also it seems perfectly possible that before too 
long atomic energy may be used to propel sub- 
marines and might even be used to propel 
guided missiles such as torpedoes. However, the 
possibilities of other forms of propulsion, such 


pedo, will become more important as time goes 
on and consequently more time and energy 
should be directed toward the improvement of 
such weapons and their countermeasures. 

Most of the research and development in 


FUTURE INVESTIGATIONS 


221 


subsurface ordnance during World War II was 
directed toward modifying and improving ex- 
isting torpedoes, since the problem of setting 
up a new line for production of these complex 
and expensive bodies was very great. But the 
limiting of research to modifications of existing 
weapons imposes very severe scientific limita- 
tions, which in peacetime can be discarded or 
neglected. It is quite evident, therefore, that 
the peacetime research should be directed 
toward more fundamental research and devel- 
opment to produce entirely new target-seeking 
torpedoes. The most appropriate method by 
which this can be accomplished is to direct 
various scientific groups to obtain all necessary 
fundamental information for the design of 
underwater ordnance. Few limitations should 
be placed on the scope of this research, since 
it is so difficult to assess the value of any 
problem before it develops. If possible, the 
specifications for new weapons should be flexi- 
ble until the problem has been formulated. Per- 
haps a proper statement of any such problem 
would be, for example, “To produce the best 
aircraft-launched antisubmarine weapon by 


1950.” Such a specification would allow sci- 
entists unhampered exploitation of all their 
knowledge and encourage them to replace old 
systems by newer and better ones. 

The possibilities of achieving a more univer- 
sal design should not be neglected, and it may 
be quite possible to produce a torpedo which 
can use any one of several homing methods, the 
proper one to be selected just prior to firing. 

Although studies and development of homing 
torpedoes to date have been almost entirely 
concerned with those employing acoustical 
homing means, other methods, including opti- 
cal, thermal, mechanical, and chemical, should 
be more thoroughly investigated. In particular, 
the properties of wakes, which are character- 
istic of all ships, both surface and subsurface, 
should be analyzed and evaluated to determine 
if they can produce a reliable signal on which 
a weapon can home. 

Obviously, any future investigation should 
also include a consideration of countermeasures 
to possible enemy weapons, as part of the value 
of any new system is the time required for an 
effective defense to be organized. 





PART V 


TRAINING AND MAINTENANCE 




Chapter 14 

ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 

By Gaylord P. Harnwell 


141 INTRODUCTION 

T he overall performance of an aggregate 
of technical components such as a ship, its 
detecting gear, and ordnance, is dependent on 
the efficiency of the human links between them. 
More frequently than not, the human elements 
are the weakest in this complex association, 
and the successful attainment of the objective 
is dependent entirely on the abilities and train- 
ing of the human participants. It was early 
recognized that a high standard of ability and 
training was essential for the effective opera- 
tion and maintenance of sonar gear and for its 
tactical utilization. The operator’s auditory and 
motor skills are vital factors in the perform- 
ance of the equipment, and the conditioning 
through training of his automatic reflexes is 
essential for his adherence to doctrine and the 
performance of his duties under the stress of 
attack conditions. 

The efficacy of the gear itself is dependent 
upon adequate maintenance and adjustment. 
The materiel problem is a complex one, neces- 
sitating on the part of technicians a familiarity 
with the mechanical and electronic components, 
the projector, and the tests necessary to insure 
correct adjustment and optimum performance. 
The operation and maintenance of the equip- 
ment are tasks assigned to enlisted personnel, 
and large numbers of comparatively new re- 
cruits had to be trained in these responsibilities. 

In addition to the operation and maintenance 
of the equipment, both officers and men are 
involved in the conduct of the attack on the 
basis of the information supplied by sonar gear. 
The problems of the officers directing the at- 
tack are difficult ones, for the information sup- 
plied by sonar is not continuous nor of the 
highest quality and requires critical assessment 
at every stage. As the target is not visible, its 
position must be inferred, and the blind conn- 
ing of an attack requires a highly developed 
visualization of a complex relative-motion prob- 
lem having a wide variety of tactical possibili- 
ties. Innate aptitudes for such tasks are un- 


doubtedly of greatest value, but training and 
experience can greatly increase proficiency in 
their performance. 

It was clearly recognized that adequate train- 
ing of all personnel participating in the anti- 
submarine attack was vital to success. How- 
ever, personnel training was a field somewhat 
removed from the research and development 
undertaken by scientists assisting the Navy at 
the outbreak of World War II. During peace, 
the field of training occupies a major portion 
of the time and attention of naval personnel 
and extremely high competence is developed in 
broad and diversified skills. But the vast ex- 
pansion of the Navy in time of war presented 
a situation which differed fundamentally from 
that of routine peacetime operation. Large 
groups of inexperienced civilians were being 
inducted and had to be given specialized train- 
ing courses. Broad competence had to be sacri- 
ficed to narrow specialization. 

The types of services rendered by NDRC 
appointees and contractors’ personnel fall in 
a number of categories. Industrial psychologists 
and specialists in training at various levels 
furnished technical advisory services in selec- 
tion and training techniques for the guidance 
of bureaus and operating units. Psychologists 
and physical scientists having academic back- 
grounds worked in close and intimate coopera- 
tion with naval training activities in the study 
of methods and techniques in use, in order to 
improve the efficient use of the brief training 
period permitted by the urgent demands of the 
Navy. Physical scientists and engineers, with 
the guidance of psychologists and other train- 
ing specialists, developed new training devices. 
This work was of maximum value when per- 
formed in close association with the training 
activities which were later to use the devices. 
Finally, civilian training personnel who were 
experienced in the problems of naval training 
activities were able to assist the research and 
development laboratories in the design of com- 
bat devices. 

On many occasions, specialists assisted in the 


SECRET 


225 


226 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


introduction of new devices and the establish- 
ment of an understanding of the basic princi- 
ples of their operation in order that Navy units 
could intelligently establish or maintain local 
training activities. Temporary training assist- 
ants were often assigned to remote commands 
for the conduct of pilot training programs until 
this work could be taken over under official 
Navy auspices. In particularly urgent situa- 
tions, civilian technicians were furnished to 
naval training activities for the conduct of 
technical courses, and in individual instances 
special advanced courses of lectures on technical 
subjects were given at the sound schools and 
other sonar training establishments through- 
out World War II. In addition to the personal 
services rendered by such men, the laboratories 
and other technical groups with which they 
were associated prepared movies, slide films, 
slides, charts, manuals, and other training aids 
to expedite and improve training programs 
under way or being established. 

142 THE SONAR ART BEFORE 
WORLD WAR II 

Underwater echo ranging dates in principle 
from World War I, but the subsequent years 
of peace did not see a sufficiently well supported 
and integrated program of research and devel- 
opment to insure adequate preparation for anti- 
submarine warfare on the scale required by 
the situation faced in 1941. There were between 
150 and 200 destroyers and a somewhat larger 
number of smaller craft equipped with the old 
types of QC gear obtained from 1937 to 1940. 
The equipment was well designed and much of 
it served throughout World War II. It was also 
the basic prototype upon which later improve- 
ments were made. The gear could be used for 
supersonic listening as well, and in fact consti- 
tuted the only equipment for this purpose 
available to most of the small group of anti- 
submarine vessels. Submarines had JK equip- 
ment which was better adapted for their pur- 
poses. The antisubmarine ordnance techniques 
had remained even more static than those for 
detection and location. The standard depth 
charges and throwing and dispensing systems 
had undergone little change between wars. 


Prior to the fall of 1941, a start had been 
made on the development of tactics and the 
training of crews in antisubmarine warfare 
[ASW] attacks. However, knowledge of the 
potentialities and limitations of underwater 
sound was limited, very few officers or men 
were familiar with ASW methods, and the 
problems of large-scale selection and training 
were not yet formulated. The effects of tem- 
perature gradients, sea state, marine life, bot- 
tom character, and water depth were largely 
unrecognized. The effects of surface-ship speed, 
target speed and target depth, and aspect on 
echo strength and character were imperfectly 
appreciated. Experience had been insufficient 
to determine the effect of range and bearing 
precision and of submarine evasive maneuvers 
on attack success. The value of listening tactics 
had been given some thought but the subject 
was a controversial one, and the limitations 
imposed by self noise, ambient noise, and bear- 
ing precision were not well understood. Thus, 
attack doctrine was in its infancy. 

The first information regarding the employ- 
ment of supersonic equipment for echo ranging 
purposes was brought to the United States by 
a commission of French naval officers in about 
May 1918. Early experiments were later con- 
ducted on the USS Fish Hawk in the New Lon- 
don area in October of that year, and a report 
of the Naval Consulting Board dated Novem- 
ber 7, 1918, states that, “Equipment located 
submarines at from 500 to 1,000 yards.” Shortly 
after the Fish Hawk tests, the New London 
Experiment Station was decommissioned. For 
several years thereafter progress was desultory, 
but beginning in 1924, experimentation by the 
Naval Research Laboratory [NRL] resulted in 
the building of two service models during the 
winter of 1926-27 which subsequently were in- 
stalled on the S-49 and S-50. A naval board 
observed and reported on tests of these equip- 
ments which were conducted during January 
and February 1927. The board’s report credits 
the apparatus with echo ranges of from 1,500 
to 1,800 yd for vessels with 18- to 20-ft draft 
and 1,000 to 1,200 yd on ships having 10- to 12- 
ft draft. Various echo-ranging equipments were 
built by NRL and by commercial laboratories 
under Navy contract in the years immediately 


THE SONAR ART BEFORE WORLD WAR II 


227 


following. By 1933-34 this developmental work 
produced reasonably rugged and reliable gear 
that was credited with submarine detection at 
4,000 yd at 15 knots (QC-1, Sub Sig). 

Training in the operation of echo-ranging 
and listening equipment during the early de- 
velopmental period was limited to Navy per- 
sonnel immediately concerned, who probably 
were largely self-taught. Initiation of the de- 
velopment of sound tactics was carried on as 
the primary assigned mission by Destroyer 
Division Sixty operating in waters off San 
Diego, California, during the last quarter of 

1935. Training of sound operators and officers 
was a secondary purpose of this mission, but 
nevertheless, in the period from September to 
December 1935, a total of 80 enlisted men and 
8 officers were given varying amounts of train- 
ing. In reporting on progress of underwater 
sound training and development in February 

1936, ComDesDiv 60 makes a number of obser- 
vations and recommendations which give an 
excellent picture for that time of the status of 
the echo-ranging art, its tactics, training, be- 
liefs, and aspirations. The report is of especial 
interest because it covers initial work in an 
essentially virgin field, the viewpoints are fresh, 
the shortcomings of the equipment and meth- 
ods are clearly stated, and desirable improve- 
ments in gear and method are envisioned. Con- 
densations and excerpts from the report of 
ComDesDiv 60 for the period September to 
December 1935 are given below. 

Sound Training 

A total of 88 officers and men have been given varying 
amounts of training (average 22.2 hours operation). A 
page has been printed, filled out, and forwarded to ships 
concerned for insertion in the service record of each 
enlisted student. The average student is far enough ad- 
vanced to complete his training by himself if given the 
opportunity. The six best operators of Division Sixty 
each has about 70 hours of individual experience. They 
averaged about 76 per cent effective in attack and 
about 54 per cent reliable in search. 

Training Methods 

Selection of student operators is worthy of special 
care. Intelligence, interest, education, hearing, patience, 
and mechanical aptitude are of importance, and per- 
haps also a natural musical bent. Basically, the training 
must develop the faculty of discriminatory hearing, the 
translation of sounds into a complete mental picture. 


Expediency requires that students should be chosen 
from the ratings which are familiar with ship control 
and associated with it throughout their naval careers, 
such as quartermasters, signalmen, etc. A general classi- 
fication (Navy GCT) of 85 and completion of tenth 
grade is a desirable minimum. 

Elementary training consisting of 20 to 25 hours of 
individual operating ordinarily brings the student up to 
the point where he can complete his education for him- 
self. However, no limit can be set for advanced training. 
After 150 hours the student is still learning, and perhaps 
500 hours will be needed. Enduring results will come 
only through a continuing program of sound training 
for students, and an established routine of practice for 
operators. Officers must be trained, especially those who 
may have to conn the ship during attack. 

Sound Tactics 

Protection of the Fleet at Sea. At present no de- 
pendence whatever can be placed upon defense sound 
screening as a guarantee of reasonable protection of 
the Fleet. A cleverly handled submarine has two chances 
out of three to get through. On the other hand, once 
the submarine’s presence and location are known, time 
permitting, her ultimate destruction can be made fairly 
certain. In training problems, aircraft made a high 
percentage of sight contacts with submarines well ahead 
of the Fleet. The “Offensive Sound Screen” tests show 
that sound-equipped destroyers could have exploited 
these contacts with 87% per cent chance of destroying 
in 1% hours all submarines spotted within six miles 
of them. 

Sound Search Attack. Head toward the submarine 
and try to get on collision course. Increase speed to 15 
knots by the time you are 600 yards from the target. 
Watch the range and bearing dials attentively and pay 
close attention to radio information from other ships. 
They are usually in a better position than you are to 
track the submarine. Be prepared for the submarine’s 
last-minute maneuvers, as they will cause you to miss 
if you do not counter them instantly. Keep the sound 
operator training across the target to catch her turn, 
and listen for the change in echo pitch (Doppler effect) 
to catch variations in the rate of change of range. You 
must listen and watch the instrument yourself, forming 
your own opinion of the submarine’s position and move- 
ments. There is no time for “passing the word” or risk- 
ing any interruptions. Run the last 120 yards (12 to 14 
seconds) “blind” by stop watch. Passing the word from 
the sound room causes lags of 50 yards or so, and you 
must be within 25 yards to get a destructive hit. Listen 
for the sound of the submarine’s propellers. Watch the 
depth indicator. “Mushy” flashes will be showing if you 
are coming up close along the submarine’s wake. The 
sudden change to a “hard” flash shows contact. At this 
moment, or at the stopwatch time that it is estimated 
this should occur, commence laying your depth charge 
pattern. A diamond of three from the racks and two 
from the Y gun should be sufficient, with 50-yd spacing. 


228 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


Look for oil or other visible evidence of the location of 
the submarine. 

Training. In training, drop two potato crates, with 
smoke pots attached, and sound sonic oscillator to 
inform submarine of the exact moment of the attack. 
Submarine then fires water slug from after tube and 
recognition bomb from projector amidships. With these 
data, i.e., the log of sound bearings from both sub- 
marine and destroyer and the courses and speeds of 
both vessels, it is possible to reconstruct the attack and 
study the effect of every maneuver of attack and 
defense. 

Problems Outstanding 

Sound Training. (1) Establishment afloat of a perma- 
nent sound operating and tactical school for officers and 
men, with a permanent staff of instructors. 

(2) Requirement that all graduates of the Radio 
Materiel school at Bellevue complete the sound materiel 
course as well as the radio course. 

Sound Tests. (1) Repetition of all tests held by 
Destroyer Division Sixty to check the results and deter- 
mine the relation of results against hours of operating 
experience and variations of water conditions. 

(2) Extension of tests to include many other uses 
to which sound seems applicable, such as detection of 
mine fields, detection of buoys, shoals, and channels, etc. 

Sound Tactics. (1) Service trials to test practicability 
of the formations and procedures. 

(2) Continuous revisions to accord with new pros- 
pects brought out in subsequent tests, service trials 
and suggestions. 

(3) Development, above all else, of improved methods 
of sound search, and of coordination with aircraft. 

Sound Materiel. (1) Correction of the few mechanical 
and electrical weaknesses in the echo-detection and 
depth-finding gear. 

(2) Redesign of 24 kc transceivers to eliminate recep- 
tion through the rear. 

(3) Provision of supersonic listening gear. 

(4) Installation of bridge sound-control stations. 

(5) Provision of radio telephones on bridge. 

(6) Installation of depth-charge racks, Y guns, and 
bomb-throwers and controls. 

(7) Development of “attack tracers,” “mechanical 
ears,” and any other devices that can expedite, simplify, 
or insure the placing of a depth charge on top of the 
submarine, under service conditions. 

Miscellaneous. (1) Study and, so far as practicable, 
actual tests of water conditions in all important areas 
of the world, to determine the probable performance of 
our apparatus under all conditions. 

(2) Continued observation of the effect of wakes, 
speed of sound vessel, marine growth and life, etc., to 
check and amplify data so far collected. 

Conclusion. The foregoing comments . . . and opinions 
and recommendations voiced are based entirely upon 
the observations and data collected in four months, of 
which fully half had to be spent in training selected 
operators before any development work could be at- 


tempted. The aim has been to bring up all points of any 
apparent consequence so that all conflicts may the 
sooner be brought to light and proved or disproved by 
actual test before the new construction program has 
advanced too far to profit by the decisions. 

Commander Destroyer Division Sixty. 

The foregoing report shows that at the be- 
ginning of 1936 the main features of the anti- 
submarine attack doctrine based on the use of 
underwater sound were outlined substantially in 
the form they were employed in World War II. 
The job of sound training done by DesDiv 60 
in 1935 was outstanding both in the number 
of personnel concerned and in the number of 
hours of training in operating the sound equip- 
ment. This was a record not to be equaled again 
for some years. The men who received their 
initial training at that time formed a nucleus 
for subsequent tactical and training develop- 
ment. However, only a very limited number of 
men in the Navy were afforded any experience 
with sound gear during this program, and ap- 
parently there was no regular adequate pro- 
vision for the earmarking and retention of men 
thus trained. The early work was that of a 
handful of enthusiastic and aggressive expo- 
nents of sound which struck a spark that did 
not encounter particularly inflammable tinder. 

Sound training had first place in the fore- 
going list of “Problems Outstanding” and the 
establishment of a permanent sound operating 
and tactical school for officers and men was 
recommended. But presumably the time was 
not thought to be ripe for this, and in the next 
few years the primary objective of the Navy 
in underwater sound was the development of 
sound tactics. For this purpose, Destroyer Di- 
vision Nineteen was ordered to operate with 
fleet-type submarines in waters of the Pacific 
Ocean, based alternately at San Diego, Cali- 
fornia, and at Pearl Harbor, Hawaii, through- 
out the years 1936, 1937, 1938, and the first 
quarter of 1939. The successive quarterly re- 
ports of the Commanding Officer of DesDiv 19 
to the Commander-in-Chief, U. S. Fleet, cover- 
ing this period, tell the story of the steady 
development of supersonic screening, search- 
ing, and attack doctrine and of submarine eva- 
sive and attack tactics. Various proposals, such 
as that for a fixed projector with a wide angle 
(cowcatcher type), were tested and rejected. 


THE SONAR ART BEFORE WORLD WAR II 


229 


performance data of echo-ranging equipment 
under various conditions were obtained, the 
disturbing effects of an own-ship’s noise at 
various speeds and of temperature gradients 
on maximum range were noted, and sound ex- 
ercises were formulated and practiced in the 
development of a satisfactory moving-beam 
search plan up to 15 knots. It was a period of 
testing and trying the underwater sound equip- 
ment under service conditions. At the close of 
the period, although the gear retained the es- 
sential form of the 1933 equipment, more rug- 
ged components had replaced those which had 
given trouble in service and a 1,000- to 5,000-yd 
dual-range scale had been substituted (1939) 
for the original 800-yd single-range scale. Al- 
though the desirability of a bridge-control sta- 
tion for the echo-ranging gear had been sug- 
gested in the DesDiv 60 tests of 1935 and 
renewed in other reports in the following years, 
progress along these lines was limited to plac- 
ing the sound stack in the chart room with 
access to the bridge through a porthole and 
installing a loudspeaker and bearing repeater 
on the bridge so that the conning officer could 
both hear and observe. Range was transmitted 
verbally by the sound operator to the conning 
officer. 

Sound operator training during this period 
was confined with trifling exceptions to men 
needed by DesDiv 19 in its development pro- 
gram. A fundamental trouble in securing suit- 
able men, however, had already become ap- 
parent as noted by ComDesDiv 19 (December 
20, 1937) as follows. 

... It has been found that superior mental types of 
non-rated men, i.e., those best qualified for training as 
sound listeners, are soon rated, leaving only the inferior 
type of non-rated men available for training. It is 
recommended that recruits at Training Centers be 
selected for mental and mechanical ability and sent to 
destroyers for training as sound operators. It is also 
recommended that a rate be established, or that a 
present rate be extended to include sound listener’s 
qualifications. 

But in spite of some deficiencies, the general 
situation was regarded as reasonably satisfac- 
tory. Underwater sound had come a long way. 
Tight defensive screening and effective attack 
doctrine had been developed and tested and a 
considerable number of destroyers and some 


cruisers were equipped with simple, sturdy 
echo-ranging gear. It was recognized that in 
order to obtain the very excellent results in 
submarine destruction reported in some of the 
training and development work by DesDiv 19, 
a very high efficiency would be required of 
sound operators and conning officers. The Navy 
was now ready for the next step, of undertak- 
ing to develop this high efficiency of personnel 
through training. 

Steps were taken to overhaul the sonar train- 
ing of the experienced personnel of Destroyers, 
Battle Force, by requiring attendance of the best 
soundman from each destroyer at a summer 
sound school held in San Diego from June to 
August 1939. The primary purpose of this 
school was to train experienced enlisted men 
thoroughly in the fundamentals of the newest 
sound-search and depth-charge attack proce- 
dures. A secondary mission of the school was 
to test the current sound-training exercises 
with a view to improvement or rejection. The 
school continued for 7 weeks, 2 weeks on shore 
at the Destroyer Base, San Diego, and 5 weeks 
at sea on the four school-ship destroyers of 
DesDiv 19. The school also accommodated sub- 
marine sound operators who were assigned on 
board the two school submarines. Approxi- 
mately 70 men satisfactorily completed the 
course. 

On August 7, 1939, the first class of the per- 
manent school, Elementary Sound Operators 
Class 1-A, was convened with 30 men and six 
officers attending. The training schedule called 
for the completion of a 6 weeks’ course, of 
which 2 weeks were shore instruction and 
4 weeks were operations at sea. Class 2-A con- 
vened on September 18, 1939, and thus was 
started a succession of elementary sound-oper- 
ator classes which continued throughout World 
War II. 

In January 1940, the materiel course of the 
Fleet Sound School at San Diego was begun. 
The course was announced as a short course in 
Radio and Sound Materiel. Radiomen, second- 
class or third-class only, were eligible. A 614 - 
week curriculum was laid out and classes were 
limited to 9 men because of restricted shop 
facilities and because the teaching work had to 
be carried on as additional duty by the staff. 


230 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


The quarterly report of the school for the 
last quarter of 1939 states that the preparation 
of two instructional pamphlets had begun : 
(1) Sound Operator’s Handbook and (2) Notes 
on the Care, Operation, and Maintenance of 
Underwater Sound Equipment . The first was 
later to run through several editions and both 
proved of primary importance for sonar in- 
struction during the next few years. 

One of the junior officers of the school had for 
some time in 1939 been giving attention to the 
requirements and design of a shore-based attack 
teacher suitable for use in training sound oper- 
ators in echo-ranging techniques and for train- 
ing conning officers in the delivery of antisub- 
marine attacks. These efforts were encouraged 
and resulted ultimately in the construction of 
an attack teacher. This equipment was installed 
in the Fleet School Building, Destroyer Base, 
San Diego, and was ready for use in December 
1940. Thus, by the early part of 1941, the West 
Coast Sound School [WCSS] was firmly estab- 
lished as a permanent sound school, with cur- 
ricula in all phases of antisubmarine instruc- 
tion. 

In the meantime, World War II had broken 
out in Europe and was being carried across the 
Atlantic almost within the territorial waters of 
the United States. The deadly effectiveness of 
the submarine as an offensive weapon, and 
especially against merchant vessels, was being 
demonstrated anew and almost daily. The ex- 
pansion of the U. S. Navy antisubmarine force, 
and with it the expansion of training activity 
to include the Atlantic coast, was an urgent 
preparatory measure. In the spring of 1941, 
the Fleet Sound School [FSS] was begun at 
Key West, Florida, with Destroyer Division 
Sixty-Six, consisting of four destroyers which 
in 1935 had operated with DesDiv 60 in the 
pioneer Navy antisubmarine development pro- 
gram in the Pacific, with Submarine Chaser 
Thirty-One (three ships), with Submarine Di- 
vision Twelve (seven boats of the R type), and 
with a Coast Guard detachment of four ships. 

At the outset, the Fleet Sound School at Key 
West had the example of the more recent train- 
ing experiences of the school at San Diego, as 
well as the use of textual material, training 
exercises, and training aids which had been 


developed by the older school. The submarine 
war, moreover, was closer and seemed more 
imminent on the Atlantic coast and lent point 
and urgency to the training work. In the fall 
of 1941, sound operator classes were being 
graduated at intervals of 5 weeks. The average 
size of these classes was approximately 50 en- 
listed men and 15 officers. This was roughly 
double the output of WCSS. This relative dif- 
ference in numbers of graduates was main- 
tained throughout the following 4 years. 

Small classes in Advanced Sound Materiel 
(6 men) and in Radio and Sound Materiel 
(10 men) were being conducted for enlisted 
men already rated for radio work, but no train- 
ing in elementary materiel maintenance was 
given at this time at Key West nor was one 
established until much later (June 1942). An 
8 weeks' course for officers which undertook to 
qualify an officer to supervise or effect any 
repairs to sound gear, subject to the supply of 
necessary spare parts, was started in December 
1941. 

In the light of present knowledge, it is clear 
that the early sound-training program pro- 
ceeded under a number of very severe handi- 
caps. There was a general lack of knowledge 
both of the capabilities of the gear under vari- 
ous conditions and also the performance that 
could be expected of the men. The criteria for 
evaluating individual and team competence 
were poor and the estimates of success based 
on them were unduly optimistic, as can be seen 
from the quotation earlier in this section. Most 
of the training was given at sea, and although 
this phase was essential, only one operator at 
a time could be trained. A shore phase was 
necessary for a large or thorough training pro- 
gram, and little information was available as 
to the proper content of such a training course. 
Standard methods had not been developed for 
selecting persons with appropriate aptitudes 
for the various sound functions, nor was it 
known whether any particular qualification 
rendered a man most likely to succeed in the 
operation of sound gear. The ASW attack-team 
concept was imperfectly formulated and meth- 
ods of training the several individuals compos- 
ing it had not been carefully considered. 

It is also evident that there were further 


IMPACT OF THE WAR ON SONAR TRAINING 


231 


very grave difficulties to be overcome even after 
a ship’s company had become proficient in sub- 
marine attacks. The maintenance of a high 
standard of performance requires constant 
practice, and opportunities for shipboard drill 
and maneuvers with submarines were rare in a 
destroyer’s schedule. This remained an impor- 
tant problem throughout World War II. Possi- 
bly the most serious situation was the lack of 
professional recognition for the job of sound- 
man. The fact that no rating existed had two 
serious consequences. The first was the absence 
of incentive to learn sound operation and the 
consequent acceptance of such an assignment 
as additional duty carrying little or no prestige. 
The second effect produced by the lack of a 
road for advancement for sound operators was 
the attrition produced in their ranks. As soon 
as a man had been aboard ship for a few 
months, he would strike for a rating in some 
other branch and be diverted from the very 
small pool of operators. Estimates of the loss 
of operators vary from 50 to 80 per cent in the 
days before the rating was established. In one 
extreme instance at the outbreak of war, a 
destroyer which actually had six men aboard 
who had received sound training had untrained 
electricians, boatswains, and cooks assigned to 
operation of its sound gear. 

14 3 IMPACT OF THE WAR ON 
SONAR TRAINING 

In anticipation of hostilities, an enormous 
program of antisubmarine construction was 
undertaken by the Navy and its extent can be 
seen by reference to Figure 1. During the initial 
period, these ships were equipped with stand- 
ard QC gear up to model QCJ and QCL. For the 
operation of these vessels prior to the com- 
mensurate expansion of the training program, 
reliance had to be placed on individual ship- 
board training without the benefit of compe- 
tent instructors. The program of expansion was 
greatly complicated by the inadequate develop- 
ment of tactics and doctrine. In consequence, 
both the combat units and those assigned to 
instructional activities had to devote much time 
to the improvement of antisubmarine tactics 
and the establishment of adequate doctrine. 
This necessarily impaired the initiation of 


suitable training programs and retarded the 
furnishing of a sufficient number of well- 
trained operators during the early years of 
World War II. It was necessary to accept com- 
promises in the quality of training that could 
be given in order to meet the demand for oper- 
ators by vessels equipped with sound gear. The 
diversion of soundmen to other assignments 
upon joining their ship further aggravated the 
situation. It has been estimated unofficially that 
from 50 to 80 per cent of the graduates of the 
sound schools in early days were assigned by 
the commanding officer of the ship to some 
duty which was considered more essential than 
that of sound operator. In consequence, for 
every two steps taken forward by the schools, 
one step backward was taken by the Navy. 

The problem of instructors was one of the 
most serious ones for the schools because of 
the great pressure for the release of all compe- 
tent operators to combat units. The instruc- 
tional methods in use were inefficient in the 
utilization of the instructor’s time. A chief 
petty officer on one side of a sound stack and a 
student on the other represents a small and un- 
progressive school. However, time was needed 
both to assemble competent instructional staffs 
and also to design equipment and devise cur- 
ricula which would permit more efficient in- 
struction. 

The pool of sound operators provided by the 
ships was quite inadequate and inferior for 
providing candidates for the expanded training 
programs in all technical specialties. It was 
necessary to draw men directly from training 
centers and although they lacked the valuable 
background of a sea experience, it was easier 
to select entrants for the schools with suitable 
intelligence and aptitude ratings. 

The expansion of the shipboard phase of the 
training program was also handicapped by the 
demands of the operating units of the Navy for 
all ASW vessels and submarines. The surface 
ships available were few in number and fre- 
quently had the oldest types of gear. The num- 
ber of submarines available for targets was so 
small that sound school graduates in the early 
days frequently had but a few minutes of 
actual individual operation at sea. Sound con- 
ditions in the areas adjacent to the sound 


ASW SONAR-EQUIPPED SHIPS TRAINED PERSONNEL 


232 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 



Figure 1 . Cumulative totals ASW ships and personnel. The charts indicate the tremendous increase 
in the number of sonar (echo-ranging) installations made and sonar personnel trained during World 
War II. The data presented have been obtained in large part from the Navy sound schools and from two 
Navy publications, the Sonar Installation Record , NavShips 900,073, and the Ordnance Vessel Register 
(BuOrd), although considerable interpretation has been necessary. No attempt has been made to show 
the number of vessels equipped with any particular type of gear; but the advents of the modern QC 
types, beginning with QCQ, and the QG-QJ (BDI) series have been indicated. Very few adequately 
trained sonar personnel existed at the outbreak of World War II; and those trained during its early 
months received only the barest essentials. Thus, the relative effectiveness of the total sonar pool was 
even greater after the establishment of the sonar rates than is indicated by a simple numerical comparison 
of the figures. 


IMPACT OF THE WAR ON SONAR TRAINING 


233 


PCOs a PXOs PER 
INSTALLATION 

Trained and 
Avoi table 


MATERIAL 
MEN PER 
INSTALLATION 


Troined and 
Avoiloble 


t 


I 


i 


i 


t 


P <• 

f 1 


SONAR 

OFFICERS PER 
INSTALLATION 

Trained and 
Avoiloble 


1 


<* 

T I 


h * 

f 1 


OPERATORS PER 
INSTALLATION 


Trained and 
Available 


1 

m 


TOTAL SONAR 
INSTALLATIONS 
IN OPERATION 




m 




II 

It 


I 1 
III 


I I I 
I I I 





• 0 © 6 © 0 © 


• • • • 

: • qv. • 

• 1 1 Q • • • • 

. on on on . 

i© 

o 

8* 


§ 

• 

• 

• 1 

• 

rj • 

• 


1941 


1942 


1943 


1944 


1945 


Figure 2. Sonar pictograph chart. As the total number of sonar installations grew, the gear was con- 
tinually redesigned and improved, and the complement of trained personnel for each equipment experi- 
enced a large relative increase. The figures, indicating the totals as of July 1 of each year, show personnel 
trained and available for assignment to sonar duties. In the period 1943-1945 the numbers are also 
substantially correct for the number of men so assigned, but in 1941 and 1942, prior to the establishment 
ot the sonar ratings, the rate of attrition determined by the assignment of sonar-trained enlisted per- 
sonnel to other and unrelated duties may have been as high as 80 per cent. The figures given for that 
period are consequently subject to correction by such a factor. The complete absence of officer training 
m the first two years should also be noted. 



234 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


schools were very poor during much of the 
year, further reducing the effectiveness of 
training through lost contacts. The evaluation 
criteria at sea were questionable, and it is dubi- 
ous whether the scores attained had other than 
incentive value. It was recognized that the real- 
ism of sea training was essential for an ade- 
quate program, but the exigencies of the situa- 
tion demanded that greater emphasis be put on 
the development of the shore phase of training 
as it was possible only in this way to attempt 
to handle the large number of students assigned 
to each class. Ameliorative efforts were di- 
rected to the development of simple instruc- 
tional devices suitable for shore use and to the 
provision of training aids and the establish- 
ment of methods that could handle large class- 
room groups. 

Since the proper functioning of the gear 
depended not only upon the competence of the 
operator but on the provision of adequate main- 
tenance, the schools’ program in materiel train- 
ing also had to be greatly expanded. There was 
little general knowledge of the intricacies of 
sonar gear among Navy radio men nor was 
there any pool of electronic specialists from 
which to draw for the training of men in instal- 
lation, repair, and maintenance. The best prac- 
tical solution which was adopted by the schools 
was to retain the most promising men from 
successive operator classes for a future pro- 
gram of materiel training. There was little 
basis for the selection of such men other than 
the intelligence and interest evinced during the 
operator course, though some consideration 
was frequently given to previous civilian tech- 
nical experience. The paucity of instructors in 
materiel was an even greater handicap than 
in operator training, and little basis for the es- 
tablishment of an adequate curriculum existed. 
The shortage of equipment led perforce to an 
undesirably theoretical trend in this training. 
The initial materiel manuals that were avail- 
able were sadly inadequate, and the nonuni- 
formity of the gear aboard different ships led 
to great confusion. 

The major emphasis in the expanded train- 
ing program was upon the enlisted men, as 
these had to be furnished in large quantities 
and they entered the schools with a minimum 


of background knowledge. However, it was 
recognized early that the skill of officer person- 
nel played a crucial role in the success of anti- 
submarine attacks and as soon as possible, care- 
ful attention was given to the officer’s functions 
and the selection and training of officer person- 
nel. Few officers, however, had the benefit of 
school training early in World War II and had 
to rely on self-instruction aboard their own 
ships. The higher basic educational level and 
the greater learning aptitude enabled officers 
who reached the schools to obtain the maximum 
of benefit during the short courses that were 
initially provided. The role of the captain and 
other officers during submarine attacks was 
not well established for many months, and it 
was not until the advent of the range recorder 
and the introduction of other conning aids that 
the concept of a sonar officer emerged dis- 
tinctly. The commanding officer of the ship fre- 
quently exercised his prerogative of taking over 
the personal conduct of antisubmarine opera- 
tions. Still later, many prospective command- 
ing and executive officers attended the schools, 
thereby gaining a familiarity with the difficult 
ASW techniques and greatly contributing to 
the success of their ships’ operations. The offi- 
cer’s role in conning and the operation of at- 
tack aids not only is a complex and essential 
one, but his thorough knowledge of all phases 
of sonar operation is important for the mainte- 
nance of the highest standards of performance 
by enlisted personnel. Failure to appreciate 
properly the effect of gear adjustment and 
sound conditions or inability to evaluate dop- 
pler or other echo character is not only prejudi- 
cial to attack success but has an adverse effect 
on the standard of performance of the sound 
crew. 

The major initial problem faced in training 
was that of meeting the enormously increased 
demand for trained personnel to operate stand- 
ard equipment. However, standard equipment 
was not entirely satisfactory, and a keen need 
was felt for the improvement of ASW gear, 
tactics, and techniques. The percentage of at- 
tack success was very small, usually reckoned 
at less than 5 per cent and the seriousness of 
the submarine menace forced the greatest ur- 
gency upon the improvement of methods to 


IMPACT OF THE WAR ON SONAR TRAINING 


235 


combat it. The proper choice of methods to im- 
prove the effectiveness of operations against 
submarines was not immediately evident and 
the many suggestions that were made had to be 
carefully studied and the promising ones thor- 
oughly evaluated. This phase of the effort, 
though not directly a matter of training, had 
important implications because the introduc- 
tion of new devices or techniques, or the modi- 
fication or improvement of old ones, involved 
the establishment of new training programs 
and methods. A decision on the adoption of one 
or another expedient frequently depended on 
the ability to secure an adequate number of 
competent personnel to render it effective. 

The advent of air participation, which even- 
tually assumed a role of comparable impor- 
tance, soon presented a number of training 
problems in which the Subsurface Warfare Di- 
vision of NDRC was of assistance. One of the 
division’s contractors developed a magnetic de- 
vice for the detection of submarines from air- 
craft, known as the magnetic airborne detector 
[MAD] and played a major role in the training 
program thus presented. The expendable radio 
sono buoys [ERSB] were also developed for 
this purpose, and their use by aircraft pre- 
sented a training problem in which one of the 
division’s contractors was of great assistance. 
Successful attacks on submerged submarines 
by aircraft alone present great difficulties, and 
another successful innovation was the com- 
bined air-surface attack. No particular device 
emerged in response to this development, but 
as the doctrine developed it became a part of 
ASW school curricula and assistance was ren- 
dered in this type of instruction. 

The surface ship continued to be an effective 
arm against a submerged submarine through- 
out World War II. The magnitude and urgency 
of the program for equipping these ships im- 
peded the introduction of any major improve- 
ments in sonar gear and World War II was 
fought essentially with the gear in existence in 
1941, with but relatively minor improvements 
as could be introduced from time to time into 
the production schedule. The greatest effort 
was applied to the most effective employment 
of essentially standard gear and the improve- 
ment of the doctrine for its use. However, many 


innovations were made in a sufficient quantity 
to be operationally significant, and in connec- 
tion with these, civilian training personnel 
were of assistance both in suggesting modi- 
fications and introducing appropriate training 
changes to take proper advantage of the im- 
proved operation thus permitted. The installa- 
tion of domes increased the permissible attack 
speed, with consequent changes in doctrine and 
instructional methods. The introduction of the 
bearing deviation indicator [BDI] improved 
the precision with which the angular location 
of the target could be determined, and the 
training in attacks was modified when center 
bearings were available in addition to the older 
bow and stern cut-ons. A number of improve- 
ments in the electronic circuits of the gear 
affecting the variation of gain with time and 
the doppler effect had a pronounced bearing on 
the type of training given operators in echo 
recognition and discrimination. The range re- 
corder, when it was introduced in quantity, was 
a major step in the improvement of attack suc- 
cess. Better ranges were available, more appro- 
priate keying intervals could be used, and the 
memory feature provided was invaluable in ex- 
trapolating to the firing point. Training in this 
device was a very important phase of work in 
the schools for both operators and officers, and 
training devices built around the recorder gave 
the first precise quantitative criteria in the 
school curricula. Depth-determining gear was 
not installed in sufficient quantity to present an 
important training problem during the period 
of NDRC participation, but some assistance 
was rendered in planning for the future incor- 
poration of such equipment in the school train- 
ing program. 

Training personnel also assisted the labora- 
tories and procuring bureaus in the design of 
those features of new gear bearing on both 
basic operation and superficial features. The 
efficiency of the operator is influenced by the 
convenience of the controls, the ease with which 
dials and indicators can be read, and the fa- 
tigue incident to prolonged watches. It was 
frequently possible to consider these matters in 
the design of equipment, and much of the newer 
sonar gear was markedly superior to the older 
installations in ease of operation. In conse- 


236 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


quence, better results could be achieved with it 
by its human operator. 

The influence of the training program was 
not restricted to innovations in the sound gear 
itself. The strategic and tactical information 
and aids produced by the laboratories had a 
marked bearing on the training programs. As 
basic knowledge of the ocean as a medium for 
the propagation of sound increased during the 
war years, officer courses in particular changed 
markedly in character, reflecting the improved 
understanding of the possibilities inherent in 
underwater sound attacks. A knowledge of re- 
fraction, reverberation, and noise provided a 
firmer basis for determining sonar ranges, the 
selection of keying intervals, the placement of 
ships on sound screens, and the conduct of at- 
tacks to avoid wake interference. 

As an understanding of the problem of the 
conning officer became more general, effort was 
seriously devoted to the provision of simple 
attack aids. Among these the antisubmarine at- 
tack predictor [ASAP] was installed in signifi- 
cant numbers, and training in this device occu- 
pied an important part in the school curriculum 
for officers. 

Although ordnance continued to be one of the 
weakest links in the submarine attack, certain 
improvements were made in the standard depth 
charge, such as increased rate of descent and 
improved fusing. These modifications likewise 
had their reaction on attack doctrine and train- 
ing programs. Assistance was given at the 
schools in the evaluation of depth-charge at- 
tacks as well as practice in laying effective 
depth-charge patterns. The introduction of pro- 
jected charges, such as the mousetrap and 
hedgehog , also affected training programs. A 
great deal of work was done in collaboration 
with Division 3 in the assessment of the suc- 
cess of such attacks during school operations 
and in the training for making effective use of 
such projectiles. 

14 4 INCEPTION OF NDRC TRAINING 
ASSISTANCE 

14,41 Selection and Training Committee 

Shortly after the establishment of a section 
within the National Defense Research Commit- 


tee concerned with antisubmarine warfare, it 
became apparent that possibly the most impor- 
tant factors in the successful prosecution of the 
war against submarines were first, the skill and 
training of the sonar operators and, second, the 
training and experience of the officers respon- 
sible for conducting the search for enemy sub- 
marines and attacks upon them. As the person- 
nel constituting the NDRC and its associates 
had been largely drawn from educational and 
engineering fields, it appeared that this group 
could be very useful to the Navy in solving the 
problems that it faced. The experience of indus- 
trial and educational psychologists in the selec- 
tion of personnel for technical jobs, including 
special auditory and intelligence qualifications, 
together with their experience in instructional 
methods and techniques, suggested that this 
group could contribute materially in the plan- 
ning and inauguration of an improved and ex- 
panded training program. Also, the laboratory 
facilities which were being provided by the 
section for the development of ASW devices 
could be drawn upon for the design and con- 
struction of suitable training devices for pilot 
use in the schools and as prototypes for subse- 
quent large-scale procurement by the Navy. 
Finally, the central liaison with the Navy pro- 
vided by the NDRC organization and the flexi- 
bility of fiscal policy and procedure enjoyed by 
the NDRC placed this group in a particularly 
favorable position to study the problem as a 
whole and initiate experimental projects in 
collaboration with the Navy. 

After consideration of the various aspects 
of the situation by the Coordinator of Research 
and Development for the Navy and by NDRC, 
the latter formally undertook a project for the 
study and formulation of aptitude tests for per- 
sonnel to be trained by the Navy in the opera- 
tion of sonic and supersonic apparatus and for 
the formulation of improved training programs 
for such persons. The undertaking was as- 
signed to Section C-4 of the NDRC, and the 
chief of that section instructed his assistants to 
interpret the problem in a broad sense as one 
dealing with the training of all personnel in the 
ultimate objective, namely, submarine detec- 
tion and destruction. Interpreted in this way, 
the first step was the assembly of a group of 


INCEPTION OF NDRC TRAINING ASSISTANCE 


237 


persons qualified by psychological, engineering, 
and mathematical skills to contribute advice 
and recommendations. The group should then, 
in consultation with the Navy, take such im- 
mediate steps as appeared feasible to familiar- 
ize itself with the problems of the ASW train- 
ing program and to acquaint itself as thor- 
oughly as possible with pertinent Navy records 
and current selection and training procedures. 
Early in December 1941, a committee on the 
selection and training of sound operators of 
Section C-4 was appointed by the chief of the 
section to constitute the advisory group indi- 
cated above. 

Arrangements were made for the first for- 
mal conference of the committee on December 
5, 1941, in Washington, with representatives of 
the Division of Fleet Training, the Naval Re- 
search Laboratory, the Bureau of Ships, and 
the Coordinator of Research and Development. 
At that meeting, a representative of the Divi- 
sion of Fleet Training presided and outlined 
briefly the projected Navy requirements for the 
next six months. The committee was informed 
of the number of sound operators that would be 
required by July 1, 1942, and was told that on 
the basis of the training program then in force 
and the anticipated attrition, this figure ap- 
peared difficult to achieve. It was suggested 
that the committee visit the sound schools and 
prepare a report for subsequent consideration. 
Arrangements were made for supplying the 
committee with representative reports of the 
Division of Fleet Training for study to provide 
background for the projected visits to the 
training activities. A representative of the Bu- 
reau of Ships emphasized that the committee 
could be of most immediate service by placing 
the emphasis of its work at that time on the 
preselection of sound operators. 

During December 1941, the committee vis- 
ited the New London Submarine Base and 
acquainted itself briefly with the basic program 
of selection and auditory testing of submarine 
personnel. A more extended visit was also paid 
to the Fleet Sound School at Key West, and the 
committee administered exploratory tests to 
determine as expeditiously as possible whether 
certain contemplated procedures would be feas- 
ible and profitable. The results of the tests were 


encouraging, and the committee recommended 
that additional work in cooperation with both 
of the sound schools be authorized for the pur- 
pose of developing these tests further and fol- 
lowing the validation of the various items in- 
volved. The committee also suggested that it be 
authorized to draw up specifications for instru- 
ments and devices likely to be of value in a se- 
lection and training program and recommend 
their development through the section’s facili- 
ties for subsequent naval evaluation. These 
recommendations were approved, and the com- 
mittee was also authorized to visit the West 
Coast Sound School in San Diego, as it was an- 
ticipated that the interruption of the program 
at that activity caused by the opening of hos- 
tilities in the Pacific would be over in the near 
future and normal operations would be re- 
sumed. 

During the week of January 6, 1942, the com- 
mittee visited WCSS. On the administration of 
tests similar to those employed at Key West, 
the committee verified that the situations at the 
two schools were quite comparable, and on 
February 20 presented the results of its find- 
ings to its naval liaison. The urgency of the 
requirement for some system of selecting op- 
erators was such that the committee was 
authorized to draw up its interim recommen- 
dations and confer with the Division of Fleet 
Training on the immediate installation of a 
selection procedure at training stations. 

It was recognized early by the committee 
that the chief difficulty in evaluating the suc- 
cess of any selection procedure would be the 
adequacy of the final criteria employed for as- 
sessing the competence of sound school gradu- 
ates. The establishment of such criteria, how- 
ever, presented a problem that could be solved 
only by continuing close cooperation between 
training specialists and the school staffs. The 
necessity for basic and varied technical train- 
ing assistance by the schools prompted the com- 
mittee to recommend the establishment, through 
NDRC contractors, of groups of competent and 
experienced personnel to work intimately with 
the laboratories and the schools in the interest 
of providing the most effective assistance pos- 
sible to the major sound training activities. The 
committee expressed its opinion that an im- 


238 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


provement in liaison between the east coast and 
west coast schools would be very advantageous. 
An interchange of officers at that time, how- 
ever, did not appear to be advisable. The hope 
was expressed by the committee’s naval liaison 
that a unified program of civilian participation 
as proposed by the committee would tend to 
bring about a closer relationship and promote 
uniformity in instructional techniques. At the 
same meeting, the question of increasing the 
emphasis on listening instruction was raised, 
and although it was recognized that this fea- 
ture was not of so great importance as echo 
ranging in antisubmarine attacks, it was con- 
sidered a valuable auxiliary technique in which 
training was a proper activity of the Navy 
schools. Information in regard to listening and 
the training of listeners obtained from work at 
the Navy schools would be of considerable value 
to other naval groups, in particular those con- 
cerned with the operation of submarines or en- 
gaged in coastal patrol or harbor defense. 

During the spring, the committee visited 
New London on several occasions for the pur- 
pose of studying questions posed by the design 
of new gear under construction in the New 
London laboratory and familiarizing itself with 
the work of training activities in that area. The 
designers of sound gear conferred with the 
committee on such matters as operator fatigue 
and the incorporation of features tending to 
provide convenience and comfort in operation, 
in order to improve operator efficiency during 
the relatively long watches which were neces- 
sary during the early part of World War II. A 
very active program of sound training was 
under way at New London, centering around 
the USS Sylph and involving the patrol activi- 
ties of the Third Naval District and the Coast 
Guard. 

It had previously been observed that many of 
the sound operators reaching the sound schools 
came from the Navy rather than from training 
stations and that these men were frequently not 
as well qualified for the training program as 
those selected by the tests which were then in 
operation. It had therefore been proposed that 
some Navy selection procedure be instituted, 
and the committee had been instructed to study 
this question and propose a feasible program. 


In order to inform itself more fully about the 
considerations involved, and incidentally con- 
tribute to the improvement of training in the 
sound schools, a questionnaire on sound opera- 
tor performance had been formulated by the 
committee and circulated to the Navy by the 
Readiness Division in April 1942. The Navy 
selection tests, which were subsequently pre- 
pared, sustained preliminary validation during 
the summer and were turned over to the Bu- 
reau of Personnel. Questions that subsequently 
arose as to the proper method for their distri- 
bution delayed their use for such a long period 
that they were never employed on the scale 
originally contemplated. 

At the July 1942 meeting of the committee, 
the preliminary results of the reports on Navy 
sound operators were presented and a number 
of interesting items were noted. The command- 
ing officers making the reports emphasized the 
fact that the operators were, in general, defi- 
cient in maintenance ability; in fact, nearly 90 
per cent indicated the lowest possible scores 
for their sound operators in this phase. In an 
appreciable number of cases, sound operators 
were considered deficient in tonal discrimina- 
tion and also in target recognition. This infor- 
mation, together with other more minor specific 
points, assisted in the proper assignment of 
emphasis both in the selection of men for sound 
training and in the program of the schools. It 
had been realized for some time that additional 
materiel instruction was urgently needed, and 
this program was shortly accelerated. The 
prominent position of auditory requirements in 
the selection tests was retained, and a program 
for improving these tests was instituted. 

On the occasion of this meeting, the commit- 
tee also added its observation that the lack of 
opportunity for promotion in the field of sound 
operation undoubtedly contributed to the large 
attrition characterizing sound operators as a 
group. The initiation of sound ratings would 
provide greater motivation for men to enter 
this specialty and remain in it, thus building up 
a skilled technical corps analogous to radio elec- 
tricians, signalmen, etc. Later, the committee 
strongly advocated the adoption of the special 
designation “sonar” in place of the longer and 
more cumbersome “underwater sound” as an 


INCEPTION OF NDRC TRAINING ASSISTANCE 


239 


important step, tending toward the formation 
of an esoteric bond among the operators and 
the establishment of esprit de corps. 

During this period, requests were made for 
assistance at the Submarine Base, New Lon- 
don, in a training program for expendable 
radio sono buoy listeners. It was proposed that 
the assistance of the National Research Council 
Committee on Service Personnel be enlisted in 
connection with the undertaking and that, in 
collaboration with the Bureau of Personnel, a 
training program be instituted and the neces- 
sary instructional material prepared. In De- 
cember, formal liaison with the National Re- 
search Council Committee on Service Personnel 
was established, and a technical aide to the 
chairman of that committee participated in 
much of the work in hand by contractors’ train- 
ing groups. 

The emphasis in the work of the committee 
had been largely on selection procedures and 
elementary training programs during 1942, 
but it had long been realized that an important 
aspect of the work which related to the ad- 
vanced phase of the ASW team training and 
provision of refresher and in-service experi- 
ence should receive more attention. As a part 
of the advanced training program in the sound 
schools, a study was made of attack-team prac- 
tice as a factor in the effectiveness of ahead- 
thrown attacks on submarines. It was later con- 
cluded that although the period that could be 
devoted to this work in the school program was 
important in familiarizing personnel with the 
attack procedure, it was inadequate to instill a 
high degree of skill in the ASW personnel. Er- 
rors even at the conclusion of training re- 
mained large, and it was found that only those 
vessels which had had an opportunity to devote 
extensive periods to practice in this type of 
attack achieved a sufficient degree of skill to 
make their effectiveness outstanding. 

It was also observed that the usual assign- 
ments of the ASW vessels permitted few oppor- 
tunities for the maintenance of training in 
ASW work. The need for some device which 
could be carried aboard an ASW vessel and 
used to provide opportunities for realistic 
training without interference with the opera- 
tion of the ship led to the recommendation that 


the development of such a device be undertaken 
by the section. As a result of the work at a con- 
tractor’s laboratory, two types of shipboard 
antisubmarine attack teacher [SASAT] were 
developed. The simpler but less realistic of the 
two was procured in some quantity and its ef- 
fectiveness demonstrated. The later provision 
of additional submarines for operation with the 
sound schools also contributed materially to the 
improvement of the sea phase of training and 
greatly enhanced the value of the over-all train- 
ing that could be given at these activities. 

Early in 1943, it became evident that as the 
selection and training procedures for operators 
had improved during the preceding year, much 
more efficient and competent sound operator 
graduates had been furnished the Navy. No 
selection procedures, however, had been fol- 
lowed in the assignment of sound officers to the 
schools, and the period of their training at the 
schools was very brief. In consequence, it ap- 
peared that a considerable increase in the effi- 
ciency of this member of the sound team could 
be effected by making a somewhat similar type 
of study of their qualifications and their train- 
ing curriculum as had been made for sound op- 
erators. As a first step, the Bureau of Naval 
Personnel directed that the selection tests for 
operators should also be used in the selection of 
sound officers from the small craft training cen- 
ters, midshipmen schools, etc. At the same time, 
the committee was requested to visit the Subma- 
rine Chaser Training Center at Miami and at- 
tempt to formulate a selection procedure which 
would be more definitely directed to the selec- 
tion of those skills particularly required by the 
sound officer for the performance of his special- 
ized assignments. In previous conferences with 
the sound schools, it had been determined that 
it would be desirable for such officers to be vol- 
unteers for this service, have a high intelligence 
rating, and, if possible, an analytical turn of 
mind and a gift for visual imagination. Me- 
chanical aptitude would also be of great impor- 
tance in the operation of special attack aids, 
and superior auditory discrimination would be 
particularly beneficial in enabling them to as- 
sist in training and in monitoring the perform- 
ance of sound operators during search and 
attack. 


240 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


A survey in September 1943 of the results 
achieved in the work indicated that they were 
not sufficiently convincing to warrant recom- 
mending the use of an improved test battery 
by the Bureau of Personnel at that time. It was 
proposed that such improvements as appeared 
most promising should be made in the battery 
of tests and greater emphasis laid on the uni- 
formity of the conditions of administration. It 
was also recommended that, in collaboration 
with the commanding officers of the schools, an 
effort be made to secure more adequate criteria 
of success wherever possible through the use of 
standardized written examinations, doppler 
discrimination and echo-recognition phono- 
graph recordings, the range recorder trainer, 
and standard scoring sheets for job perform- 
ance. 

By the early summer of 1944, records of a 
sufficient number of student officers under the 
new program were available for a resurvey by 
the committee, and it was agreed that the steps 
which had been taken during the first half of 
1944 had greatly improved the experimental 
results. It was felt that the test battery ap- 
peared very promising and that a complete re- 
port should be submitted to the Bureau of Per- 
sonnel to enable it to institute whatever modi- 
fied selection procedures seemed desirable. Fur- 
ther validation was thought to be advisable, but 
the number of officers being selected for school 
attendance was rapidly dropping and it was 
not evident that significantly improved results 
could be achieved in time to be of use to the 
Navy during World War II. One of the tests in 
the experimental battery dealing with relative- 
movement problems had proved quite discrimi- 
nating, and it was recommended that a separate 
report be prepared on this test for submission 
via the office of the Commander-in-Chief in case 
it might be thought applicable to other special 
groups of Navy personnel. 

During the autumn of 1943, the success of 
the ASW operations in the Atlantic and the 
emphasis on submarine work in the Pacific sug- 
gested that greater attention be given by Divi- 
sion 6 to prosubmarine problems, and the chair- 
man of the committee visited the training ac- 
tivities of both the destroyer and submarine 
forces at Pearl Harbor. However, the work of 


the committee on ASW selection had been made 
available earlier to the Submarine School, and 
the program that had already been followed at 
that activity had reached such a stage that 
further study by the committee in this field did 
not seem justified. 

The role of the committee throughout its ex- 
istence was that of an advisory group of spe- 
cialists who were available for consultation 
within a special field to the NDRC and the 
Navy. The committee enjoyed the additional 
privilege of submitting recommendations as 
these appeared appropriate in the course of its 
observations and experience. As indicated in 
the foregoing section, the committee periodi- 
cally reviewed the progress of the various pro- 
grams which it had initiated or with which it 
had been associated. It also provided special 
liaison for the training groups of the section’s 
laboratories with the office of the Commander- 
in-Chief and the various naval bureaus in- 
volved in different aspects of training in the 
sonar field. 

The experience of the members of the com- 
mittee in both industrial and academic selection 
and training work was found to be very largely 
applicable to the situations faced by the Navy 
in its sonar training program. It was appreci- 
ated early that wartime conditions imposed 
severe limitations upon systematic procedures 
and that expeditious approximations had to be 
adopted, particularly in the early work. Ade- 
quate assessment of the value of many of the 
proposals that were made was frequently pre- 
cluded by the operating duties assigned to the 
naval training activities with which the com- 
mittee was working. The committee’s lack of 
previous experience in the special problems 
confronting the Navy in wartime was a handi- 
cap which was gradually overcome by its fre- 
quent visits to the sound schools and similar 
organizations. As this intimate collaboration 
developed, the Navy also acquired a better ap- 
preciation of the way in which such specialized 
civilian advisory personnel could be most ef- 
fectively utilized. The committee enjoyed most 
wholehearted cooperation from the training ac- 
tivities with which it was associated, and upon 
the establishment of a mutual understanding of 
the many obligations and limitations to which 


INCEPTION OF NDRC TRAINING ASSISTANCE 


241 


both the Navy and the civilian personnel were 
subject, effective cooperative programs were 
carried out. 

The difference in the instructional situation 
between a civilian organization and the Navy 
presented many problems to the naval training 
activities in accepting the recommendations 
that from time to time resulted from the com- 
mittee's studies and observations. The training 
courses were in most cases much shorter than 
would have been desirable because of the ur- 
gent need by the Navy for trained sound men. 
The conflicting requirements of the Navy and 
training activities for training vessels, new 
types of gear, and other special facilities often 
imposed limitations on the equipment available 
to the sound schools which materially reduced 
the effectiveness of the training that could be 
given. Naval personnel in charge of classroom 
and laboratory instruction had frequently had 
little experience in imparting their knowledge 
and skills to students, and the many other ur- 
gent considerations affecting naval assign- 
ments, particularly during the earlier stages of 
the war, permitted little consideration of this 
point. As facilities became available and the 
manpower situation less critical, the schools 
and other training activities rapidly improved 
in effectiveness under the able guidance of the 
officers successively assigned to their command. 

Frequent meetings with the committee's 
naval liaison served to focus its attention on the 
most important and pressing problems as they 
arose in the development of the Navy’s training 
program. Its meetings also provided an oppor- 
tunity to profit by the advice and experience of 
representatives from the National Research 
Council’s Committee on Service Personnel and 
later NDRC's Applied Psychology Panel. The 
channel for the interchange of opinion and in- 
formation thus afforded was mutually helpful to 
the specialized civilian groups engaged in as- 
sisting the Navy in the field of technical selec- 
tion and training during World War II. 

The early work of the committee was almost 
exclusively directed toward the training of op- 
erators for antisubmarine warfare, as this was 
the problem of paramount importance during 
the war with Germany. The emphasis in the 
training program was on search and attack and 


the maintenance of the gear employed for these 
purposes. In the later stages of World War II, 
the prosubmarine aspect of the Navy’s work 
in subsurface warfare became the field in which 
the committee could be of more assistance. 
Here, however, the extent to which previous 
work with the committee could be applied re- 
duced somewhat the number of remaining fun- 
damental problems in the committee’s field. The 
difference in naval cognizance for elementary 
and advanced training in this work also re- 
duced somewhat the committee’s effectiveness. 
The Submarine School at New London, at which 
elementary sonar training was conducted until 
the autumn of 1944, was under the operation of 
the Bureau of Personnel. New construction 
training and the advanced and refresher phases 
were under the direction of the submarine com- 
manders of the two Fleets, and this division of 
responsibility and the wide geographic separa- 
tion between training units made it somewhat 
more difficult to obtain an adequate overall pic- 
ture of the program. With the concentration of 
submarine sonar training at WCSS in the 
autumn of 1944, the contractors’ training 
groups were in a better position to lend their 
specialized assistance, and from time to time 
the advice and suggestions of the committee 
were drawn upon. 


14 ‘ 4 ’ 2 Contractors’ Training Groups 

In addition to the centralized exploratory 
and advisory functions performed by the Selec- 
tion and Training Committee, effective assist- 
ance was rendered to training activities 
through projects assigned to contractors. Al- 
though this phase of NDRC assistance was 
largely in the hands of the training groups as- 
sociated with the major laboratories, invalu- 
able contributions to training were made by the 
NDRC — BuShips Field Engineers and the 
Antisubmarine Warfare Operations Research 
Group [ASWORG]. The central organization 
of the Field Engineers and their many local 
representatives played an important part in 
facilitating the activities of training personnel 
and they themselves contributed greatly to ma- 
teriel training problems. ASWORG was helpful 


242 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


in directing attention to training opportunities 
and in furnishing information upon which in- 
structional material could be based. One of 
their representatives also devoted several 
months to the organization and conduct of an 
air training problem at Norfolk to provide 
needed assistance not otherwise available. 

The major laboratories of the section fur- 
nished the scientific and engineering talent 
needed for training-device development and 
also served as essential bases of operation for 
psychologists and industrial training special- 
ists. Much of their work lay outside the labora- 
tories. In the cases of the larger schools they 
had offices and other facilities in the school 
buildings. They also roamed far afield in re- 
sponse to various requests for assistance, but 
the backing, prestige, and procurement facili- 
ties of the laboratories were invaluable to them 
on any assignment. 

The training activities of contractors may 
be considered as being of two types: introduc- 
tory training and general training. Introduc- 
tory training is assistance rendered in the as- 
similation by the Navy of combat equipment 
devised and introduced by the several labora- 
tories. This is an essential final phase of any 
program of technical development and all the 
laboratories undertook work of this nature. The 
Harvard laboratory was concerned largely with 
BDI training, the Mineola laboratory with in- 
troductory training in MAD, and the Woods 
Hole laboratory with the initial bathythermo- 
graph [BT] program. However, introductory 
training on a particular device was seldom con- 
ducted exclusively J)y the developing laboratory 
because of geographical factors. 

The general training program of furnishing 
assistance to Navy training schools and com- 
mands was one of the principal projects as- 
signed the San Diego laboratory. From the 
spring of 1942 until the assignment of the con- 
tract to the Navy in the spring of 1945, a large 
and active group of training assistants worked 
with the West Coast Sound School. From the 
autumn of 1942 until the summer of 1944, a 
somewhat smaller group was stationed with 
the Fleet Sound School in Key West. From the 
autumn of 1943 until the spring of 1944, a 
training group was conducted in association 


with the Submarine School at New London. This 
group was then transferred to the New London 
laboratory which had previously been engaged 
in some training-device development and had 
served as host to the training group in that 
area. The San Diego and New London labora- 
tories maintained numerous small groups of 
training assistants and individual specialists 
for varying periods of time at a number of 
coastal and island stations. Their activities will 
be mentioned further in connection with spe- 
cial projects. Occasions arose for sending train- 
ing assistants on special missions before ade- 
quate formal provision for such civilian assign- 
ments with the Navy was established. The 
training activity antedated that of the Field 
Engineers or ASWORG, and, unlike those 
groups, training assistants seldom proceeded 
under Navy orders. This was in general dis- 
advantageous, though many individuals who 
worked informally during the early days were 
highly effective. 

The training groups in the laboratories and 
on detached assignments were kept apprised 
of one another’s activities through periodic re- 
ports issued chiefly by the San Diego labora- 
tory. These reports were of great value in 
maintaining unity of effort and general cogni- 
zance of the common problems by all partici- 
pants in the training program. 

14 5 SELECTION PROGRAMS 

14,5 1 Selection of Operators 

First Operator Selection Plan 

As a result of the preliminary observations 
by members of the Selection and Training Com- 
mittee it was thought by the research men that 
the following standardized tests would have 
some degree of usefulness in determining apti- 
tude for the rapid learning of sound operation. 

1. Otis Mental Ability Test (intelligence). 

2. Bennett Mechanical Comprehension Test, 
Form AA. 

3. Seashore Sense of Pitch Test, First Edi- 
tion. 

4. Seashore Sense of Intensity Test, First 
Edition. 


SELECTION PROGRAMS 


243 


5. Seashore Tonal Memory Test, First Edi- 
tion. 

6. The NDRC Personal History Inventory (a 
listing of items of the social, educational, 
and occupational factors in each candi- 
date’s background). 

These tests were administered to 109 sonar 
student operators at WCSS in January 1942, 
and were later administered to 92 additional 
students at FSS during the same month. Both 
the test scores and the performance data were 
given to statistical advisers for computation 
and report. The results of the computations 
were available by the middle of March 1942. 
The pressure to secure men was so great that 
the resident psychologist at WCSS made ten- 
tative use of the tests during February and 
early March for the selection of recruits from 
the San Diego Naval Training Station. This 
was done rather hesitantly because the validity 
of the tests was as yet unknown. Later valida- 
tion reports showed that this preliminary use 
of the tests had been justified and had saved 
the Navy from the inclusion of a large number 
of sonar students who would have come in 
without the intelligence, mechanical, and tonal 
aptitudes necessary for adequate job perform- 
ance. 

Scores from the various individual tests and 
combinations of the test were correlated with 
every available job criterion (measure of per- 
formance on sonar), such as written examina- 
tions, attack-teacher grades, and overall rat- 
ings made by the sound schools on each man. 
This was the only feasible procedure, although 
it was adopted with much trepidation since the 
criteria were known to be unreliable because of 
the nature of the curriculum, the lack of objec- 
tive grading technique, and the poor control of 
both shore and ship phases of training. The 
correlations gave some encouragement and the 
first selection plan was designed on the basis of 
a two-screen process. The intelligence test was 
used as the first screen on all available candi- 
dates. Only men who could secure a better-than- 
average score were accepted. The second screen 
was applied only to the men who had passed 
the first screen ; it consisted of the mechanical 
comprehension test and the tonal tests aver- 
aged together. Approximately the lower one- 


third of men taking the second screen tests 
were rejected. 

The selection psychologists met in confer- 
ence with the U. S. Navy Bureau of Navigation 
on March 24, 1942. At this meeting it was 
agreed to use the plan substantially as devised, 
except that the Navy General Classification Test 
[GCT] would be substituted for the Otis mental 
ability test, to avoid a multiplicity of test de- 
vices in the hands of the selection officers who 
would soon be under an avalanche of screening 
jobs for all branches of the Service. The Navy 
GCT was also a general intelligence test, and 
later data showed that it correlated highly with 
the Otis scores (correlation coefficient of 0.82 
to 0.91). 

At the same meeting, arrangements were 
made for the resident NDRC psychologist to 
travel the circuit of the naval training stations, 
meeting the selection officers, demonstrating 
the selection procedure, inspecting the equip- 
ment and test locations, and following through 
with continuous assistance to see that the dif- 
ficulties in administration were overcome and 
that the screening procedure was carried out as 
accurately as possible. During 1942 and 1943, 
this contact with the training stations was con- 
tinued. The old hand-scored test answer-sheets 
were replaced by a method of machine scoring 
and tabulating which allowed selection officers 
to use mass-screening procedures and keep up 
with the growth of war mobilization. 

In the meantime, the resident psychologist at 
San Diego established an office with subordi- 
nate personnel, permitting extensions of the 
first statistical studies. Many sonar students 
were coming from other sources than the naval 
training stations. There were transfers from 
ships’ crews. The U. S. Coast Guard was now 
engaged in antisubmarine warfare, and no pro- 
vision had been made to screen Coast Guard 
students. At first these students from miscel- 
laneous sources constituted as much as half of 
the classes. Many were completely pitch-deaf, 
and some did not have either the general or 
mechanical intelligence to learn the job ade- 
quately in the time allowed. The commanding 
officer of the school authorized the NDRC psy- 
chologist to apply the new selection method to 
all students entering from other than recruit 


244 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


centers, and a large proportion of the failing 
men were dropped before they could consume 
the badly needed space in the training program. 

During the first year of World War II, sev- 
eral verifying statistical studies were made on 
much larger samples of men, to see if the origi- 
nal study, based on a relatively small sample 
of operators, was a valid one. These further 
researches showed that there was no need to 
change the original opinion of the research 
men that the selection devices were essentially 
good. There was obvious room for improve- 
ment, however, and a statistical program of 
test and experiment, with modifications of the 
original tests and new ones suggested in the 
course of the work, was in continuous opera- 
tion. It was difficult to obtain time in the sched- 
ules of the conduct of experimental work as the 
schools operated under great pressure to fur- 
nish operators at the maximum rate. Training 
operations came first and improvement second. 
Such experimental work as was accomplished 
resulted from constant vigilance by psycholo- 
gists to make use of every minute and the 
wholehearted cooperation of instructional offi- 
cers who appreciated that the schools' product 
was dependent on receiving the best possible 
candidates for training. 

Revised Operator Selection Plan 

The original operator selection methods were 
used with only minor changes until the spring 
of 1944. Several important defects were dis- 
covered as time went on. The original plan al- 
lowed some men to enter sonar training who 
were pitch-deaf, because the tests were scored 
by averaging mechanical comprehension with 
tonal discrimination, and a man could compen- 
sate for a bad tonal score by an unusually high 
mechanical comprehension score. The refine- 
ment of doppler grading by means of doppler 
drills and tests revealed the weakness of this 
method. The Bureau of Personnel also wished 
to investigate the possibility that one of the 
tests in the standard naval battery given at 
selection centers might be substituted for the 
Bennett test, thus saving needless overlap on 
testing time. There was also the difficulty that 
the originally authorized GCT had been 
changed, and the new basic battery of naval 


tests had unknown validity for sonar operation. 
Furthermore, the Seashore sense of intensity 
and sense of pitch tests showed a low level of 
statistical reliability. 

As a result of these conditions, it was de- 
cided to plan a two-screen selection procedure 
wherein the first screen would combine the 
general and special comprehensional require- 
ments, and the second screen would be re- 
stricted to tonal aptitude, thus making it im- 
possible for pitch-deaf cases to get sonar train- 
ing. 

The following tests were chosen for experi- 
mental administration to some sonar classes 
then in WCSS, although they were already a 
selected group under the old plan. 

1. Navy General Classification Test (general 
intelligence). 

2. Navy Reading Test (comprehension of 
technical reading). 

3. Navy Arithmetic Test (arithmetical rea- 
soning) . 

4. Navy Mechanical Aptitude Test (mechani- 
cal comprehension and visualization). 

5. Bennett Mechanical Comprehension Test, 
Form AA. 

6. A new NDRC Sonar Pitch-Memory Test. 
The sonar pitch-memory test took the place of 
the Seashore tests. 

The results of experimental administration 
were satisfactory except that the Bennett test 
proved to be less reliable than the Navy me- 
chanical aptitude test, and the latter was there- 
fore substituted for it. The new plan was ap- 
proved by the Bureau of Personnel in May 
1944 and was instituted by directive to the vari- 
ous naval training centers having selection 
offices. To pass the first screen, a candidate had 
to secure at least an average score on any three 
of the four basic naval tests. 

14 o ‘ 2 Selection of Sonar Maintenance 
Men 

It was evident very early that inefficient use 
of sonar was often the result of maladjustment 
of the equipment, if indeed it were not an actual 
casualty, and though the operator might be well 
trained in the routine execution of attack doc- 
trine, he frequently did not know when his 


SELECTION PROGRAMS 


245 


equipment was out of order. It was not pos- 
sible in 5 weeks of training to give the average 
student operator sufficient knowledge of such 
a complicated electronic device to enable him 
to maintain maximum serviceability. The 
Navy, therefore, decided to train about one- 
third of the operators to make repairs and ad- 
justments, assuming that a ship with four or 
more sonarmen would then have at least one 
man who could service the gear. The course was 
given at each sound school, following the train- 
ing course for operators, and graduation with 
a satisfactory mark carried with it later an in- 
crease in both rating and pay. About one-third 
of the top graduates from each operator class 
were selected to take the 10 weeks’ maintenance 
course. 

It was gradually realized that the top third 
of the operators was not necessarily the best 
source of candidates for maintenance instruc- 
tion. Therefore a composite selection plan was 
designed, using each of the following factors on 
an experimental basis. 

1. Navy General Classification Test (intelli- 
gence) . 

2. Navy Arithmetic Test. 

3. Bennett Mechanical Comprehension Test. 

4. Educational background (units of educa- 
tion in mathematics and sciences from high 
school and college). 

5. Average grade made on three operator 
written examinations. 

This new selection plan for maintenance can- 
didates was installed in December 1942 at 
WCSS, and was administered by NDRC psy- 
chologists for the duration of World War II. 
Later a similar plan was established at the 
FSS. This method of administration was neces- 
sary because there was no trained classification 
officer located at either sound school until the 
fall of 1944, and there were no other places 
where sonar maintenance selection was needed. 

Selection of Sonar Officers 

At each sound school sonar officers were 
taught sonar operation, interpretation of sonar 
information, and the tactical use of sonar and 
antisubmarine attacks. In the sea phase, the 
officers were given practice in conning ships 


during practice attacks on tame submarines. 

Some of the officers were poorer operators 
than the enlisted sonarmen who were in the 
same classes, and some found it impossible to 
make adequate auditory discriminations, to 
visualize the tactical situation, or to execute 
the required navigational maneuvers. At first 
these men were allowed to go through to their 
permanent assignments without being dropped. 
Later the Bureau of Personnel provided a 
means whereby the schools could report the un- 
satisfactory performance of particular men 
and they were accordingly reassigned to other 
duties. 

The work in the officer program was handi- 
capped because it is not possible to secure a 
validation coefficient for a selection plan unless 
the final job grade is a reliable one and it is 
very difficult to compute a prediction coefficient 
if the job is constantly changing. Both of these 
handicaps, however, had to be faced because 
there was continuous development in attack 
doctrine throughout the first two years of 
World War II and corresponding frequent al- 
teration in the duties of sonar officers. No job 
analysis was ever stable, and it was seldom 
that the men were graded on the same basis 
for more than a few successive classes. Officers 
were generally graded even less consistently 
and objectively than were enlisted men. The 
grades were generally contaminated, from the 
psychologists’ standpoint, by factors not con- 
cerned with the technology of sonar, such as 
ability to command men, aggressiveness, and 
appearance. It was for these reasons that it was 
not possible to achieve a selection plan for 
officers which had the objective selectivity at- 
tained for enlisted men. 

During most of World War II the sonar 
officers had been routed through the Submarine 
Chaser Training Center at Miami, before being 
sent to the sound schools. This activity gave 
some sonar training and was in a position to 
effect some selection of officer candidates for 
the more advanced sound schools at Key West 
and San Diego. In March 1943, WCSS recom- 
mended that the NDRC sonar selection plan for 
operators be applied to sonar officers. The 
recommendation was adopted and issued as a 
Navy directive, but it was not presumed that 


246 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


the selection procedure covered all of the officer 
requirements. The intelligence requirement was 
considered to be adequately covered by the 
more stringent educational standards for all 
naval officers. The commanding officer at Miami 
requested and was furnished with the NDRC 
sonar testing materials. In practice, the scores 
from the tonal tests and the mechanical com- 
prehension test were tempered by further 
knowledge concerning a man’s performance on 
the sonar attack exercises. 

In 1943, an advisory NDRC psychologist de- 
signed a selection research program involving 
some 13 tests from Navy batteries and other 
sources. These included such devices as officer 
general qualification tests, mechanical compre- 
hension tests, tonal tests, mathematical com- 
prehension tests, and visualization tests. A 
statistical study of the predictiveness of each 
test was to be undertaken and the battery was 
to be shortened to include only those with the 
highest values. The research study consumed 
most of the summer of 1943, with NDRC psy- 
chologists working at both San Diego and Key 
West. The period was one of rapid change in 
attack doctrine and the job grades on officer 
performance were at the time largely influenced 
by the previously mentioned nontechnical qual- 
ifications. 

Five tests which survived the elimination 
process were administered to 88 men at San 
Diego and 60 at Key West and a report of the 
results submitted to a meeting of the Selection 
and Training Committee with the Navy in 
Washington. It was decided that the results 
were not sufficiently assured to warrant a posi- 
tive recommendation. It was, however, strongly 
recommended that the research be continued, 
and that additional work be done to strengthen 
the reliability of the grading of officer perform- 
ance in the schools. 

Shortly after this decision, the range re- 
corder trainer [QFL] was completed and gave 
more objective scores on interpretation of re- 
corder traces and firing errors on the tactical 
range recorder. At San Diego, the NDRC 
psychologists, with the approval of the com- 
manding officer, designed a complete set of 
written examinations for officers on the tech- 
nical aspects of sonar attack navigation, in ob- 


jective form. A similar set of examinations was 
already in existence at Key West. It was hoped 
that these might improve the predictions for a 
further selection study. The general form of 
these examinations was used for the duration 
of World War II. In addition, the officers were 
now using the new NDRC doppler drills and 
tests, which gave a very reliable grade for the 
most important of the tonal requirements in the 
job performance. A new selection test was cre- 
ated by the NDRC psychologist, namely, the 
relative movement test for measuring aptitude 
in continuously visualizing the relative posi- 
tions of two vessels proceeding at various 
speeds and on various courses. It was also found 
that the Seashore tests were subject to several 
acoustic and administrative errors which lim- 
ited the reliability of tonal scores when used as 
an aptitude test. The NDRC sonar pitch-mem- 
ory test was standardized and experimentally 
applied to over 600 recruits, with the result that 
the statistical reliability was almost doubled as 
compared with that of the Seashore tests. 

The second research selection program used 
the residue of tests from the first program, ex- 
cept that the relative movement test was added 
and the NDRC sonar pitch-memory test was 
substituted for the Seashore tests. This time it 
was decided to make tonal discrimination a sep- 
arate and independent requirement. It was 
planned, therefore, to devise a first screen for 
the comprehensional aptitudes and a second 
screen for the tonal aptitude. 

The tests in the first screen, after elimination 
of the poorer selective devices, were : 

1. Bennett Mechanical Comprehension Test. 

2. Relative Movement Test. 

3. Army Air Force Visualization Test. 

The second screen consisted of the NDRC 
sonar pitch-memory test. 

After experimental analysis of this plan, rec- 
ommendation was made to the Bureau of Per- 
sonnel for its use, with a passing score for 
Screen I such that by rejecting one-half of the 
candidates with the lowest selection scores, the 
worst 10 to 12 per cent of sonar officers would 
be surely eliminated, and the remaining stu- 
dents would be all of passable aptitudes. The 
tonal score on Screen II required that every 
officer be average or better on pitch-memory 


ANTISUBMARINE WARFARE TRAINING 


247 


discrimination, and this was exactly the same 
as the requirement later installed for enlisted 
sonarmen. The selection method was accepted 
and installed in part, with the understanding, 
however, that still further work would be done. 
By the end of 1944, the induction program at 
Miami was considerably curtailed, most of the 
sonar officers were already in service, and the 
need for any further work had largely passed. 

146 ANTISUBMARINE WARFARE 
TRAINING 

Work with the Sonar Schools 

The major contribution to the sonar training 
program was made in association with the 
sound schools. A resident psychologist was pro- 
vided at WCSS in the spring of 1942, and there- 
after the group grew by the accretion of addi- 
tional industrial psychologists, engineers, and 
training specialists, until it reached eight or ten 
members early in 1943. By the summer of 1942 
a similar but smaller group was established at 
FSS at Key West. Both of these groups were 
concerned with the selection programs de- 
scribed in the preceding sections, and this was 
their principal assignment during the earlier 
days of their establishment. 

By the autumn of 1942, however, a consider- 
able portion of their time was given to assisting 
the school officers in training activities. The im- 
portance of this function rapidly increased and 
could be considered their major assignment by 
the spring of 1943. While living at the schools 
and working intimately with the officers and 
men in charge of instruction, they obtained a 
very thorough familiarity with the training 
problems and with the Navy’s methods of con- 
ducting training activities. The civilian groups 
concerned themselves with the analysis of the 
school programs into separate learning prob- 
lems, the study and solution of these problems, 
and the improvement of general training meth- 
ods and techniques. Their assistance was wel- 
comed in the preparation of lecture material 
and in the development of presentation of tech- 
niques for both laboratory and classroom exer- 
cises. Many suggestions were also made for the 
introduction of films, charts, and other training 
aids and devices. 


At both schools it was evident that the max- 
imum use was not being made of detailed ob- 
jective grading methods, and continued em- 
phasis was placed upon this point. The basic 
handicap was the lack of firm criteria of accom- 
plishment in the different shore and sea phases, 
and marked progress resulted from the intro- 
duction of synthetic training devices in the 
shore phase. These devices, which will be de- 
scribed in Section 14.7, incorporated certain 
features suggested by resident training groups 
which were designed to facilitate precise evalu- 
ation of student performance. They were 
largely successful in this objective, particularly 
in the preliminary weeks of sound training. The 
existence of such devices did not in itself insure 
the scoring of students in individual accom- 
plishments. The tendency of Navy instructors 
was to form an overall subjective impression of 
a man’s success, and this impression was not 
only frequently biased by irrelevant factors but 
it did not serve to insure the necessary detailed 
competence in the various skills required of an 
operator. 

The sea phase of operation was subject to 
this criticism in a much greater degree and 
there the problem of evaluating success was 
even more difficult and the precision of evalua- 
tion was insufficient to judge properly an at- 
tack’s success or failure. 

However, experienced observers could assess 
the individual performances of operators and 
officers, and significant grades could be given. 
Through a study of these observations, a check 
list for evaluating sea performance was intro- 
duced at FSS in 1943 and led to noticeable im- 
provement in the efficiency of the sea phase of 
instruction. This was clearly indicated by com- 
parative tests of operator proficiency made over 
an extended period by ASDevLant on selected 
operators from the two schools. Although these 
operators were presumably chosen from groups 
of comparable standing at each school, the per- 
formance of operators from FSS was found to 
be consistently superior to that from the school 
in San Diego. This was largely attributable to 
the fact that detailed attention was given at 
Key West to each of the many functions in 
which an operator must be proficient and to the 
assurance through the checkoff system that 


248 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


such proficiency was gained. A similar program 
of close scrutiny of operating details by an ex- 
amining board was instituted a year later at 
WCSS, and thereafter their graduates achieved 
equally good ratings by ASDevLant. 

In addition to assistance in instructional 
techniques, the formulation of periodic and 
final examinations was given careful study, and 
suggestions were made for improving their dis- 
crimination between good and poor operators 
and for increasing the ease with which they 
could be scored. Standardized examinations 
permitted more adequate comparison of attain- 
ments between succeeding classes and provided 
a firmer basis on which to evaluate improve- 
ments in training techniques. 

The training groups at the schools worked as 
closely as possible with those divisions of the 
laboratories which were concerned with the de- 
sign of training devices. Frequently these 
groups would present to the laboratory their 
observation of the need for a device to facilitate 
training in a particular skill. They would then 
work with the laboratory in the design of a 
pilot model of this equipment and, upon its de- 
livery to the school, study with small classes its 
efficacy in training and devise efficiency tests in 
its operation. This work would almost invari- 
ably uncover certain inadequacies in either the 
design or functioning of the equipment and 
modifications or redesign would be suggested. 
Several units of the improved equipment would 
then be constructed and a larger program of 
incorporating it in the school curriculum under- 
taken. The training group would assist in the 
training of instructors for this equipment and 
work out exercises and drills. A more complete 
study would be made of learning, manuals 
would be written for the instructors and stu- 
dents, and examinations formulated. The lab- 
oratory would, in general, furnish the installa- 
tion, maintenance and operating manuals for 
the school, and other installations as these 
might be requested by the Bureau of Personnel. 
In those cases where the device was of interest 
to the Bureau of Personnel, through its general 
concern with sonar training, or had possible ap- 
plications to other training fields, manuals and 
recordings were furnished the bureau and as- 
sistance rendered when necessary in its intro- 


duction at other training establishments. As- 
sistance in the writing of manuals for both 
operators and materiel students was the prin- 
cipal assignment of several individuals at the 
schools. Instructional manuals in general ema- 
nated from the schools themselves and after 
submission to the Commander-in-Chief, were 
issued as official Navy publications. Civilian as- 
sistants participated extensively in the compila- 
tion, editing, and revision of the material. 

With the advent of newer types of sonar 
gear, the problem of adequate maintenance 
texts at the schools became particularly critical. 
A considerable group of men and officers was 
assisted by an engineering member of the train- 
ing group in the capacity of editor in the prep- 
aration of a sonar maintenance manual. This 
undertaking occupied 8 months, and when is- 
sued in January 1945, consisted of more than 
800 pages. A distribution of 5,000 copies was 
made to other maintenance and training activi- 
ties. 

From time to time, various specialists were 
attached to the training groups at the schools 
and elsewhere for the purpose of giving lec- 
tures at an advanced level to sonar and prospec- 
tive commanding officers. These lectures were 
intended chiefly to provide scientific back- 
ground for ASW doctrine. 

The establishment of maintenance courses in 
the two schools early in World War II was 
greatly handicapped by the lack of suitable 
naval instructors, and as the situation was a 
critical one, civilian specialists in electronic en- 
gineering were located and retained to form a 
nucleus of materiel instructors at the two 
schools. These staffs numbered six to eight at 
each school for a period of a year or more, and 
rendered invaluable assistance during the early 
period of materiel instruction. Later, the train- 
ing program for electronic specialists and radio 
technicians furnished naval personnel to take 
over these assignments, and civilian instructors 
either joined the staffs of the development lab- 
oratories or received other assignments within 
the Navy. 

14.6.2 Subsidiary ASW Training Projects 

The major effort in general training was 
made through the training groups associated 


ANTISUBMARINE WARFARE TRAINING 


249 


with the sound schools but training assistance 
was furnished by a number of smaller groups 
and individuals on special assignment from 
time to time as opportunities were presented. 

For several periods of a few months’ dura- 
tion, training assistants worked with harbor 
defense activities at both Fisher’s Island and 
San Pedro. Experience gained in work with the 
sound schools contributed to the establishment 
of curricula and the preparation of lectures and 
examinations at these harbor defense activities. 
Training assistants were likewise assigned for 
intervals of several months to the Antisubma- 
rine Warfare Instructor’s School [ASWIS] at 
Boston on the utilization of new training de- 
vices and techniques, and to the Tenth Fleet 
for liaison with civilian training groups and 
laboratory device-development programs. Sim- 
ilar assistance was rendered on a somewhat 
longer term basis to shakedown and refresher 
training activities with COTCLant at Norfolk 
and Bermuda, and with COTCPac at Seattle, 
San Francisco, and San Pedro. These men con- 
tributed in a number of technical ways through 
their assistance in the introduction of training 
devices, maintenance assistance on attack teach- 
ers, and the provision of liaison with civilians 
in schools and laboratories. 

A training assistant on special assignment to 
the Bureau of Ships, beginning in the autumn 
of 1943, assisted in the inauguration of the 
Sonar Equipment Log which was a periodic 
materiel publication circulated to RMO’s for 
the purpose of keeping them abreast of current 
materiel developments. A training assistant 
was assigned to ComDesPac in the autumn of 
1943 primarily for the introduction of ship- 
board attack teachers, but in the hope that he 
would also be generally useful both in the local 
training program and in bringing the facilities 
of the laboratories more effectively to bear on 
particular problems encountered in the Pacific. 
This assignment was a very successful one and 
resulted in a number of suggestions which im- 
proved the operation of this equipment in the 
Southwest Pacific. 

At a somewhat later date, the assistant with 
ComDesPac gave his principal attention to sea- 
air rescue work and was largely instrumental 
in the adapting of the expendable radio sono 


buoys to this use. The application of ERSB to 
this service grew out of ASW operations with 
CVE-DE hunter-killer groups. The method 
there in use was known as raser (radio sonar 
echo ranging) because of the way in which the 
buoys were used to receive sonar signals and 
transmit these back to the echo-ranging ship 
by radio. In rescue operations, survivors from 
a ditched aircraft release one or more of the 
buoys, and searching aircraft or surface vessels 
obtain RDF bearings on the radio carrier at 
ranges of the order of 15,000 yd for surface 
vessels, and approximately five times that fig- 
ure for aircraft. As a result of the experi- 
mental work conducted during the spring of 
1945, an urgent and extensive program of 
equipping destroyers operating with fast car- 
rier task forces was undertaken for the pro- 
jected strike against Japan. Surface vessels, 
submarines, and aircraft were equipped with 
the necessary buoys and receivers and were 
trained and in readiness for operation at the 
time hostilities ceased. The program of experi- 
mental and operational tests continued and 
training manuals and movies for instructing 
personnel were planned for subsequent naval 
procurement. 

The other phase of training which was con- 
cerned with the introduction of new combat 
devices likewise presented many occasions for 
extended tours and brief assignments of 
groups and individuals to naval activities. 
These activities can be illustrated more con- 
veniently by considering them in terms of the 
device being introduced. A few representative 
instances of such training programs are given. 

Bearing Deviation Indicator [BDI] 

The BDI, which was developed by HUSL, 
required modification of training methods and 
assistance in introduction. At first this assist- 
ance was conducted on a very informal basis 
through occasional lectures given at training 
schools by members of the laboratory staff. 
Modifications of shore-based attack teachers to 
incorporate BDI were requested and the lab- 
oratory assisted in the design and production 
of these. ASWIS requested assistance in the 
preparation of lectures on the BDI and the lab- 
oratory assisted in this and in the training of 


250 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


certain instructors on the ASWIS staff in the 
operation of the equipment. The Antisubmarine 
Warfare Training Center [ASWTC] at Nor- 
folk also requested assistance in the prepara- 
tion of BDI training aids and the laboratory as- 
sisted in the inauguration of a training course. 
A dynamic demonstrator was constructed, and 
later several units were procured for the sound 
schools to improve materiel training in this 
device. As the basic equipment appeared in 
larger quantities on naval vessels, it became 
evident that the informal lectures were not 
reaching a sufficient number of interested naval 
personnel. To meet the need for training men 
in installation and maintenance, a group of 
field engineers and sonar officers was sent to 
Harvard for a one-week course. Beginning in 
February 1944, six of these courses were con- 
ducted, covering trace interpretation, details of 
adjustment, operation, installation, the location 
of trouble, and conduct of tests. 

Expendable Radio Sono Buoys [ERSB] 

The introduction of radio sono buoys was 
another occasion for which training assistance 
was required. In the spring of 1943, the New 
London laboratory inaugurated a training pro- 
gram and furnished instructors in the ERSB 
school which was established by ComAirLant 
in Norfolk. They gave introductory training, 
trained instructors, and formulated outlines of 
courses, lectures, and demonstrations. A train- 
ing device for the ERSB was designed and 
several units were furnished to air commands. 
Assistance was also given in the organization 
of training exercises and the evaluation of stu- 
dent performance. With the advent of the di- 
rectional buoy, further assistance was given in 
introductory training, and a directional radio 
sono buoy trainer was designed and used for 
training in the laboratory. This was later fur- 
nished to the training activity at Norfolk and 
assistance was given in its incorporation in the 
air training program of that activity. 

Magnetic Attack Director [MAD] 

The training work undertaken by the Air- 
borne Instruments Laboratory at Mineola was 
an example of aid given to the Navy in an en- 
tirely novel field. Naval personnel were not 


familiar with the MAD, and with the advent 
of this equipment the training problem became 
of great importance. The laboratory built train- 
ing equipment, laid out curricula, and hired 
and trained instructors. The work was carried 
out in the laboratory essentially as an experi- 
mental project since there was no precedent in 
this field. Regular courses in the principles of 
operation of the equipment were begun in Sep- 
tember 1943, and a more or less continuous 
series of courses was conducted until June 
1944. Army personnel were assigned to the 
school from time to time, and it was found 
that the syllabus was equally applicable to both 
Services. Three separate courses were taught. 
The first was intended for pilots, and covered 
two weeks of material devoted to operating 
capabilities and limitations, coordinated use 
with sono buoys and radar, and practice in the 
recognition and discrimination of signals. The 
second course was for aviation radio men who 
functioned as operators of MAD aboard air- 
craft. This course was of two weeks’ duration 
also and covered the recognition of signals and 
their distinction from spurious indications, ad- 
justment and operation of the gear, and coor- 
dination with the pilot. The third course was 
for aviation radio technicians who were con- 
cerned with maintenance and repair. It was of 
five weeks’ duration and was a comprehensive 
review of the electronic principles of operation 
and a thorough course in maintenance and 
troubleshooting. Nearly 350 officers and men 
from both Army and Navy were indoctrinated 
in one or more of these courses. As a by-product 
of the training activities of this laboratory, 
certain special courses were undertaken for 
training in the magnetic compensation of air- 
craft and the use of the magnetic attack trainer. 

Bathythermograph [BT] 

The initial installation of bathythermographs 
aboard naval vessels gave rise to one of the 
first instances in which training assistance was 
requested. The Woods Hole laboratory assisted 
ASWIS in 1942 in the training of a few student 
officers who were sent down to the laboratory 
for a few days at a time. They were given lec- 
tures and reading material, and shortly the 
curriculum was expanded to occupy about one 


ANTISUBMARINE WARFARE SONAR TRAINING DEVICES 


251 


week and was attended on the average by ten 
men at a time. Other groups of BT officers 
were assigned to the laboratory for periods of 
a month at the request of the Bureau of Ships, 
and these men were given more extensive train- 
ing in the use of the BT. Before the training 
of ASW specialist officers was terminated in 
1944, approximately 600 men had received in- 
struction through the efforts of the laboratory. 
In addition to this formal instruction program, 
a number of laboratory personnel from both 
Woods Hole and San Diego made extensive 
tours of the North and South Atlantic, the 
Caribbean, and the Mediterranean, to increase 
their knowledge of this device and the effec- 
tiveness with which it could be used. At a later 
stage, both laboratories provided training as- 
sistants who worked with the Operational 
Training Commands on both coasts, assisting 
in both the training and materiel problems 
which were encountered. The program with 
submarines was more extensive and will be 
mentioned in a later section. 

Manuals and Publications 

An instance of a somewhat different type of 
cooperative assistance was furnished in the 
field of materiel. In addition to the manuals 
prepared for school use and instruction, urgent 
need was felt by the district and Service forces, 
as well as shipboard maintenance men, for 
more adequate information on sonar gear. In 
some instances no manuals whatever were 
available, and in others the documents were 
fragmentary or outdated. The existing manuals 
were not standard in content, style, or technical 
level. It became increasingly evident in 1943 
that faulty maintenance was one of the chief 
causes of inefficient sonar operation, and an 
urgent request was received to assist in the 
preparation of more adequate manuals and the 
establishment of a standard by which Navy 
suppliers could be guided. A considerable num- 
ber of officers were assigned to the work, and 
through their participation a knowledge of the 
problems and techniques involved was dissem- 
inated within the Bureau of Ships. Approxi- 
mately 12 manuals and equipment logs were 
produced, averaging about 300 pages apiece. 
These were printed under direct Navy con- 


tract and distributed by the Bureau of Ships. 

One further publication undertaking is 
worthy of note. This was the Training Group 
Handbook assembled in January 1944. The 
major portion was secured as loose leaves from 
the Manual for ASW Field Engineers, as this 
manual was directly applicable to the problems 
encountered by training groups and assistants 
assigned to naval activities. The handbook con- 
tained reference material for the indoctrination 
and training of members of the civilian staff as 
well as data needed on assignments to the vari- 
ous naval establishments. It proved invaluable 
to all training activities and represented a most 
significant contribution to training by the Field 
Engineers. 


14 7 ANTISUBMARINE WARFARE SONAR 
TRAINING DEVICES 

14,7,1 Training Aids 

One of the important contributions made by 
the contractors' laboratories to the training 
program was the design and procurement of 
training aids and devices. Training aids took 
many forms and were supplied not only to 
schools but to the Navy units engaged in train- 
ing and they contributed materially to the ef- 
fectiveness with which instructors could impart 
information to large classes of enlisted men and 
officers. 

Profiting by industrial experience in visual 
education, a number of moving picture films 
were produced. Some were produced by the 
laboratories with advice and assistance from 
the Navy and in other instances films were pro- 
cured by the Navy, utilizing technical experi- 
ence furnished by the laboratories. These films 
formed part of the sonar curriculum at the 
school and were of even greater value in re- 
fresher training with the Navy and at advanced 
bases. Slide films were also made by the labora- 
tories. These dealt chiefly with newer types of 
auxiliary equipment, such as the BT and RSB. 
The facilities of the laboratories were also 
drawn upon for producing lantern slides and 
an extensive library of these was built up which 
assisted materially in the school curricula. In 


252 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


addition to visual aids of this nature, charts 
and animated demonstrators were built for the 
purpose of displaying surface vessel and sub- 
marine maneuvers. 

These visual aids were supplemented by au- 
ditory ones, and the recording facilities of the 
laboratories were well adapted to the prepara- 
tion of this type of training aid. For some 
purposes, lectures were recorded at one train- 
ing activity and made available to another. The 
playing back of these lectures was also helpful 
on many occasions in improving instructors’ 
presentations and techniques. In addition to 
this application, phonograph recordings of sea 
echoes and ship sounds formed the basis of 
training in echo and sound recognition. Exten- 
sive programs were carried out in the labora- 
tories for the acquisition of representative 
echoes and ship sounds, and these were later 
edited and assembled in graded series adapted 
both to school and advanced-base instruction. 

A wide variety of small, inexpensive devices 
were also produced which either assisted in 
training curricula or were aids to the operators 
or officers during different phases of their 
training or practice. 


14,72 Representative Training Devices, 

Shore Phase 

In addition to the demonstration devices and 
training aids considered above, considerable 
effort was expended in the development of 
training devices for large-scale student use 
during the shore phase of instruction within 
the schools. It is not possible in as brief an 
account as this to describe all of these devices 
that were used in the course of World War II, 
but representative ones will be considered 
briefly to illustrate the type of assistance ren- 
dered and the improvement in these devices 
that resulted from increased knowledge on the 
part of laboratories and schools as to the most 
effective manner in which they could be em- 
ployed in training. 

Primary Bearing Teacher 

It was recognized during the spring of 1942 
that a need existed for a simple primary single- 


student trainer for giving practice in the ma- 
nipulations required of a sound operator in 
response to auditory stimuli. Work on a pri- 
mary bearing teacher, which was later given 
Navy designation QFE, was begun in June 
1942. It was submitted for evaluation by the 
Navy in July and a request was soon received 
for 50 of these devices, which were supplied 
through a subcontractor. They were completed 
in about 6 weeks and immediately put into use 
at both sound schools. Subsequently about 500 
were built and used at various training ac- 
tivities. 

Since sound school classes were large, there 
was no opportunity for students to obtain the 
necessary thorough drill in fundamentals with 
the other training facilities available to the 
schools. Although the primary bearing teacher 
was not intended to duplicate conditions of 
work on an actual sonar stack, it did permit 
extensive drill in the correct procedure for op- 
erating and reporting while listening for ech- 
oes. A crude approximation of a doppler effect 
was also provided. With these devices, a stu- 
dent’s reactions could be brought to the point 
where they were largely automatic and correct 
operational habits could be developed before 
going on to advanced training. 

In practice, three students were generally 
trained on this device at one time. The first of 
these was the control operator who reported on 
contacts, contact bearings, cut-ons, mid-bear- 
ings, target width, bearing drift, and doppler. 
The standby operator, using a checker’s record 
sheet, checked for errors made by the control 
operator. The problem setter, or instructor, was 
generally a senior student who set the ship’s 
course, target bearing, and doppler. After con- 
tact, he gave the appropriate commands while 
turning the ship smoothly to head for the tar- 
get. When the students were all of more or less 
the same degree of competence, the three oper- 
ators would change places until all became fa- 
miliar with the various procedures. 

Advanced Bearing Teacher 

In point of time, the advanced bearing 
teacher, Navy designation QFD, antedated the 
primary bearing teacher, but in the normal 
curriculum and in the orderly development of 


ANTISUBMARINE WARFARE SONAR TRAINING DEVICES 


253 


a training program it represented an advanced 
stage of training, presenting more realistic 
sounds and providing practice in more of the 
functions of the sound operator. Like the pri- 
mary bearing teacher, however, it suffered 
from being an individual student trainer and 
from a certain artificiality in the controls and 
auditory signals. 

This device was suggested in early conversa- 
tions with officers of WCSS, and design and 
construction of a pilot model were undertaken 
early in 1942. By June 1942, three of the de- 
vices were in use at WCSS, and a month later 
two were delivered to FSS. Within the next few 


The training handwheel was of the same size 
and had approximately the same friction and 
moment. Either long or short standard keying 
intervals could be used. The problem presented 
to the operator could be allowed to develop 
automatically or could be modified as desired 
by the instructor’s intervention. Two ships, a 
submarine target and an attacking surface ship, 
were simulated by the device. The student imag- 
ined himself in the sound room of a destroyer 
seated before the QC stack, and he operated 
the controls as he would operate them there. 
When contact was established, he attempted to 
stay on the target as his own ship maneuvered 



Figure 3. Primary bearing teacher. Left, student’s side. Right, instructor’s side. 


months, 20 more were obtained from a subcon- 
tractor. In all, about 170 of these devices were 
built and used by the Navy during the first two 
years of World War II. 

The advanced bearing teacher was particu- 
larly suited for continuing the training of stu- 
dents who had had several days’ experience on 
the primary teacher. On the advanced teacher, 
their training was conducted under conditions 
more closely resembling those of actual opera- 
tion. At the conclusion of their drills with this 
instrument, their habits were sufficiently well 
formed that they were prepared to make the 
most effective use of team training on the at- 
tack teachers and at sea. The student’s side 
closely resembled the older types of QC sonar. 


to intercept the submarine, and he furnished 
the same reports that he would on board ship. 

At the beginning of the problem, the subma- 
rine was 2,300 yd distant from the destroyer 
and had an angular width of 71/2 degrees. Con- 
tact could be made at any true or relative bear- 
ing at the option of the instructor. The course 
of the destroyer could be altered by the in- 
structor, if desired, as the problem progressed. 
The relative motions were such that the de- 
stroyer passed about 150 yd in front of the 
submarine, and at the point of closest approach 
the apparent width of the submarine was 24 
degrees. Throughout the attack, realistic sounds 
characteristic of operating QC gear were pro- 
duced, including the ping with its reverbera- 


254 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


tion, echoes, and water noise. Means were pro- 
vided for automatically changing the echo to 
produce the doppler effect appropriate to the 
chosen attack pattern. The echo automatically 



Figure 4. Advanced bearing teacher. Left, stu- 
dent’s side. Right, instructor’s side. 

followed the ping after an interval which cor- 
responded to the actual range of the submarine. 
Stronger echoes were obtained if the axis of 
the sound beam was directly on the target than 


instructor could introduce many of the distrac- 
tions and difficulties which the sonar operator 
would experience at sea. The instructor was 
able to set up the problem and let the run 
proceed automatically, or he could simulate a 
wide variety of other attack patterns by mak- 
ing one or more of the following adjustments: 
(1) the pitch of the echo with respect to rever- 
beration, (2) the loudness of the echo with 
respect to reverberation, (3) the rate at which 
the reverberation decayed, (4) the loudness of 
the water noise, (5) the heading of the attack- 
ing ship, (6) the bearing of the submarine. The 
problem ordinarily ran for about 11 minutes. 

Primary Conning Teacher 

The primary conning teacher, Navy designa- 
tion QFH, is another instance of the advanced 
realistic type of single-student trainer, differ- 
ing, however, completely in nature from the 
advance bearing teacher. It was intended prin- 
cipally to provide preliminary practice for 
conning-officer trainees in dealing with the rel- 
ative motion problem presented in an antisub- 
marine attack by a surface craft equipped with 
standard echo-ranging gear. No sounds were 
produced by this teacher as it was not intended 
for training in echo recognition, but equivalent 
information of about the same character and 



Figure o. Primary conning teacher. Left, submarine side. Center, control panel. Right, destroyer side. 

if it was on one side or the other, and the reliability was presented visually to the trainee, 

echo strength diminished with target distance. In the usual operation of the attack teacher 

By regulating the various controls provided on (QFA), unequipped at that time with BDI, it 

the instructor’s side, as shown in the figure, the was found that the information essential for 


ANTISUBMARINE WARFARE SONAR TRAINING DEVICES 


255 


plotting was too erratic and confused to pro- 
vide a good basis for learning plotting methods. 
By means of the conning teacher, it was possi- 
ble to hold extensive drills in plotting for an 
entire class with continuous increase in the 
level of difficulty. Students could thus be brought 
to the point where they could plot efficiently on 
the attack teacher during their training with 
that device. 

The conning teacher was a device with which 
an ASW officer could acquire practice in mak- 
ing all the judgments necessary in conning an 
attack against a submarine. The surface vessel 
and submarine had complete freedom of ma- 
neuver, subject only to the limitations imposed 
by the tactical parameters of the vessels and 
the information properly available to them. 
The conning-officer trainee was seated at one 
end of the instrument, which is shown in the 
accompanying figure, and imagined his ship to 
be at the center of the coordinate screen which 
he viewed. The range (maximum value 2,000 
yd) and the bearing of the submarine were 
indicated to him visually by a small round 
light spot which appeared intermittently on the 
screen. The frequency with which this spot 
appeared was approximately that at which he 
could expect to obtain information from a good 
sound operator. On the panel before him, the 
conning officer was provided with engine and 
rudder controls with which he could change the 
speed and course of his ship. Appropriate de- 
lays were incorporated in the rudder control 
to simulate the lag in the response of the ship 
to its helm. The rate of turning was also a 
function of ship's speed and was chosen to be 
appropriate for the class of ship that the in- 
strument was intended to represent. 

The opposite end of the machine was the 
submarine control station and was occupied by 
the competitor, or instructor. The submarine 
was imagined to be at the center of that screen 
on the course indicated by the course dial. The 
movement of the destroyer with respect to the 
centered submarine was again indicated by a 
small round light spot which appeared contin- 
uously, and the screen was calibrated by radial 
lines for bearing but was without circles for 
range. Controls for changing the speed and 
course of the submarine were provided, again 


with suitable delays in the turning rates. At 
the beginning of each exercise, or competition, 
the submarine positioned itself and, in the case 
of elementary exercises, the officer conning the 
submarine provided additional information to 
the ASW officer in training to simplify his 
operations. The exercises actually used varied 
all the way from the simple case in which the 
trainee was given the speed and course of a 
submarine which was not maneuvered, to those 
free competitions in which the instructor re- 
garded himself as a submarine commander and 
employed all the evasive tactics at his command. 
It was possible to apply various criteria in 
evaluating the success of an exercise. The scor- 
ing of a mousetrap problem might be made on 
the ability of the conning officer to maneuver 
his ship so as to be on the correct bearing at 
the instant of fire, or alternatively the conning 
officer might be held responsible for the time 
of fire as well. 

The conning teacher was used by various 
training commands to fulfill a number of dif- 
ferent functions besides that for which it was 
originally designed. It was used for training 
in elementary and advanced plotting. It was 
used for both depth charges and forward- 
thrown attacks on straight courses and on 
maneuvering submarines. It was also used as 
a problem generator in CIC instruction. In one 
of the schools it was used as an ASW instruc- 
tional device by assigning a full attack team of 
four members to each unit. The conning officer 
conned the attack as he would on an attack 
teacher, watching the gyro-compass repeater 
and true sound bearing and, acting as his own 
helmsman, manipulated the rudder and speed 
controls. The sound operator called off ranges 
and center bearings, as indicated by the light 
spot, keeping the true sound bearing continu- 
ously adjusted and recording intermittently the 
reading of the range dial. The plotting officer 
made a Halifax or time-range plot from the 
data furnished by the operator. The problem 
setter made the initial setting of the submarine 
and maneuvered the target as required by the 
problem. 

The first five units of this device were com- 
pleted in June of 1943 and furnished the sound 
schools and the Submarine Chaser Training 


256 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


Center. One hundred and four additional units 
were later procured by the Navy and furnished 
directly to ASW training centers. 

Tactical Range Recorder Teacher 

The training devices that have been described 
above contributed materially to the rate at 
which trainees could receive the shore phase of 
their instruction, but they were essentially in- 
dividual training devices, requiring the pres- 
ence of an instructor for each student. As the 
shortage of instructors was one of the chief 
handicaps faced by the schools and other train- 
ing activities, it was desirable to develop de- 
vices which were more economical of instruc- 
tors’ time. The devices previously described had 
the additional failing that they provided no 
permanent accurate record of the student’s per- 
formance and therefore fell somewhat short of 
ideal training instruments. 

The tactical range recorder teacher, Navy 
designation QFL, was the earliest of the group 
trainers which provided a permanent record 
upon which the performance of the student 
could be accurately scored. With the advent of 
the range recorder, an instructor at WCSS 
recorded on a phonograph disk the reverbera- 
tions and echoes of a practice attack on a sub- 
marine. By means of a special electronic keying 
circuit and amplifier, this recording was played 
back to the range recorder, thus reproducing 
the traces originally made at sea. Recorders 
were not at that time sufficiently plentiful to 
permit the construction of a training device 
built around them. However, ASW officer of the 
Readiness Division of COMINCH recognized 
the importance of such a trainer, and a training 
assistant was assigned to collaborate with the 
USS Sylph to develop the idea in order that a 
trainer would be available as soon as range 
recorders could be furnished in sufficient quan- 
tity. On the basis of this work, one of the divi- 
sion’s laboratories constructed five units, and 
later 50 units were procured through a Navy 
laboratory. 

As the name implies, the trainer was intended 
to provide instruction and practice for the op- 
erator of the chemical recorder in evaluating 
traces and reporting at proper intervals the 
motion of the target and the time of fire. Re- 


cordings were made of practice attacks at sea 
using the laboratory facilities and were repre- 
sentative of the various types of attacks. Five 
albums containing approximately 50 records 
were furnished as part of the trainer. 

A typical training unit consisted of five range 
recorders to which information was furnished 
by the playback and electronic system. The 
realistic reproduction of the recorder traces 
and the accompanying sounds was a primary 



Figure 6. Tactical range recorder teacher, as 
installed at the U. S. Fleet Sonar School, San 
Diego. 


aim in the design of the equipment. The record 
that was presented to each student enabled the 
instructor to assess accurately the student’s 
performance and indicate to him, both at the 
time and in subsequent conferences, the errors 
perpetrated. Case studies were made at the 
training activities on the effectiveness of the 
device as an instructional aid, and assistance 
was given in the establishment of the trainer 
in school curricula. As in the case of all the 
other training devices, instruction manuals 
were prepared covering installation and main- 
tenance as well as instructional use. 

This was the earliest and one of the most 
successful of group trainers and met with en- 
thusiastic approval by all training activities. 

Echo Recognition Group Trainer [ERGT] 

Early in 1944, the WCSS recognized a grow- 
ing need to establish a special training program 
in the recognition of target echoes as heard 


ANTISUBMARINE WARFARE SONAR TRAINING DEVICES 


over sonar gear. The size of the classes indi- 
cated that the trainer should be capable of ac- 
commodating 15 or 20 students, and it was 
essential that the recordings be highly correct 
in character. In addition, a permanent record 
should be kept of the accuracy of the student’s 
judgment and the time required for him to 
formulate it. Finally, the trainer should be such 
that it would be unnecessary for the instructor 
to interrupt the auditory pattern of the exer- 
cise during its presentation. The first model of 



Figure 7. Echo recognition group trainer, as 
installed at the U. S. Fleet Sonar School, San 
Diego. The recorder, filters, amplifier, and play- 
back system are shown at the left, and some of 
the students’ stations at the right. 

such a trainer was designed and placed in op- 
eration at the school in April 1944, its per- 
formance was carefully studied, and two addi- 
tional models were later built for other training 
activities. 

The trainer comprised a phonograph play- 
back system, a number of student station keys, 
and a monitor recorder. The recordings and 
the exercises conducted with them were de- 
signed particularly to improve the abilities of 
the sound-officer and enlisted personnel in the 
following functions: (1) doppler judgment, 
including degree, (2) distinction between wake 
and submarine echoes, (3) detection of faint 
submarine echoes, (4) identification of cut-ons, 
and (5) proper reporting of judgments as made 
during an attack. In the operation of the train- 


257 


ing program, a number of students were pre- 
sented with a carefully prepared sequence of 
sea recordings interspersed with related lec- 
tures. During the presentation of the record- 
ings, each student registered his judgment 
silently by moving a station key. These move- 
ments were recorded simultaneously for all 
students and the instructor on the monitor re- 
corder. When each selection was over, the in- 
structor compared the students’ records with 
his own in assessing the members of the class. 
A predetermined code allowed the instructor to 
interpret the broken and continuous lines pro- 
duced on the record by the movement of the 
students’ keys. In addition to the album of 
recordings, instructor’s manuals and mainte- 
nance manuals were prepared on this device, 
and it formed an essential element in the train- 
ing courses at the schools. 

Training in echo recognition was found to 
be such an essential feature in operator and 
sound officer training that a request was re- 
ceived to modify the training in this function 
so that it could be given at advanced bases with 
a minimum of equipment. In response to this 
request, studies were made of the feasibility 
of using the same recordings and employing 
mimeographed forms which were marked in 
pencil by the student in lieu of the keys and 
the recorder. It was found that the training so 
provided was equivalent to that of the echo 
recognition group trainer, except that the time 
necessary for the student to reach his decision 
could not be made a matter of permanent rec- 
ord. It was considered that the training was 
satisfactory without this feature, and 20 al- 
bums of recordings and instruction manuals 
were prepared and issued at the direction of 
the Bureau to advanced bases during the winter 
of 1944. 

Group Operator Trainer 

As the classes of sonar operators increased 
in size, at both of the sound schools the allow- 
ance of advanced bearing teacher units was 
found to be inadequate. The demands made on 
the staff instructors by such unit-training de- 
vices were also prohibitive. In consequence, a 
request was received for the construction of a 
group trainer in sonar operation which would 


258 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


enable one instructor to handle a class of ap- 
proximately 10 students at a time. An oppor- 
tunity had been afforded by the installation of 
the British mass procedure teacher at Key West 
to evaluate the possibilities of such a device 
and a counterpart of this British trainer was 
the first suggestion. It appeared feasible, how- 
ever, to improve considerably on the mass pro- 
cedure teacher, and the most desirable features 
of the advanced bearing teacher and tactical 
range recorder teacher were drawn upon in the 
design of the group operator trainer. Standard 
sonar gear was available in sufficient quan- 
tity by 1944 to permit its use for student 
stations. This afforded greater realism of in- 
struction and also permitted the teaching of 
various stack adjustments which had not been 
possible previously with the advanced bearing 
teacher. 

Each student station was provided with a 
standard QGB or QJB stack with a few of its 
circuits revised to correspond to those of the 
problem generator. The master station, or prob- 
lem generator console, was provided with three 
panels. On the left-hand panel were the concen- 
tric bearing scales on which a bug indicated the 
true center bearing of the submarine. On the 
center panel, ten small identical receiving in- 
struments indicated the respective bearings on 
which the students’ projectors were trained. 
Below these instruments were control knobs 
which regulated the various sound effects, the 
depth of the submarine, and other factors of 
the problem. On the right-hand panel were a 
monitor bearing recorder, control buttons for 
the two-way communication system between 
instructor and students, and certain control 
switches. After the problem was started, the 
relative movements developed independently of 
the instructor and students. The cam arrange- 
ment controlling the problem was so constructed 
that the surface ship was conned properly for 
the attack. Six different attacks were included 
in the repertoire of the trainer and they were 
grouped in pairs representing attacks and re- 
attacks. The instructor could select at will any 
one of the three pairs by an adjustment through 
the side of the console. The sound effects were 
more realistic than those provided by the ad- 
vanced bearing teacher. 


Units were installed at both sound schools in 
1944 and were incorporated in the regular cur- 
riculum of the schools. From time to time re- 
quests were received for the incorporation of 
additional features such as the FXR-4. As the 
program represented a developing one from 
the fall of 1943, the maintenance and instruc- 
tion manuals originally provided were consid- 
ered as interim issues, and a final manual was 
not furnished until the termination of the lab- 
oratory’s activities. 

Underwater Sound Attack Teacher 

Although NDRC had little part in the devel- 
opment or modification of the attack teacher, 
Navy designation QFA, no account of sonar 
training would be complete without a mention 
of it. As was stated in a previous section, it 
was recognized during the earliest days of the 
operation of WCSS that a shore-based device, 
portraying in the best synthetic manner the 
major features of an ASW attack, would be 
an essential training instrument. The attack 
teacher differs from the devices previously dis- 
cussed in that it was originally designed as a 
training device for all members of the ASW 
team. The first model was built by the Mare 
Island Navy Yard using an old range keeper 
and on the basis of its performance a rede- 
signed attack teacher was procured by the Navy 
from the Sangamo Electric Company in quan- 
tities sufficient for the schools and all other 
training activities of any size. 

The equipment was designed to simulate in 
miniature the operation of sonar gear, and in- 
cluded the range recorder, the attack predictor, 
and conning stations. It consisted primarily of 
a mechanism integrating the functions of the 
various attack stations, providing appropriate 
sounds, and also projecting on a screen conven- 
tionalized images of the surface ship and target 
throughout their maneuvers. The resultant 
equipment provided a means for training sound 
operators in the manipulation of sonar gear 
and for instructing sonar officers and conning 
officers in the performance of their several 
functions. This simulation of supersonic echo 
ranging was achieved by a suitable arrange- 
ment of optical, electromechanical, and elec- 
tronic apparatus. The simulated ocean consisted 


ANTISUBMARINE WARFARE SONAR TRAINING DEVICES 


259 


of a screen upon which were projected the 
images of the surface ship and submarine, to- 
gether with a band of light periodically tra- 
versed from the ship across the screen at a rate 
proportional to the velocity of sound and in a 
direction controlled by the sound operator. The 
path of the band of light represented the wave 
front of the sound beam, and when it encoun- 
tered the ship image representing the target, 
an echo was returned to the sound stack. A 



Figure 8. Console of the underwater sound at- 
tack teacher as installed at the U. S. Fleet Sonar 
School, San Diego. The rear of the console can 
be partially seen in the mirror, which was used 
to increase the projection path in this particular 
installation. 

major feature of the conning controls was the 
correct simulation of the tactical parameters 
of the ships concerned and, in consequence, 
realistic training was given to the officers. The 
training device was a most complete and val- 
uable one and formed the backbone of the shore 
phase of team training in ASW. 

In the work of the training assistants with 
the schools and in the early advisory work of 
the committee for the Bureau of Ships, certain 
minor contributions were made to the design 


and operation of this trainer. Observations on 
the apparent beamwidth of the supersonic pro- 
jector indicated certain modifications in the 
interest of correct presentation. An adjunct 
representing an assisting ship was designed 
and provided to WCSS to a,id in the training 
on that type of attack. An auxiliary projector 
to provide the instructors and observers with 
an azimuth grid covering the synthetic ocean 
was found to be of assistance, particularly with 
the early models of this teacher, and a number 
of these were designed and furnished by a 
laboratory. 


14,7,3 Representative Training Devices, 

Sea Phase 

The sea phase of training in ASW operations 
is an essential advanced stage in any course to 
qualify operators and officers for combat oper- 
ations. The attack teacher provided training in 
the integration of various members of the at- 
tack team ashore, but it was not sufficiently 
realistic to take the place completely of such 
team training aboard ship. The sea phase of 
training, however, presented additional prob- 
lems which were found to be very difficult of 
solution under the conditions encountered at 
the schools. In general, only one operator at a 
time could obtain direct participatory training 
aboard ship, and in consequence the periods of 
actual operation for any one man were very 
brief. It was difficult for instructors aboard 
ship to assess properly the performance of the 
sound operator because of the many distrac- 
tions and the dependence of his performance 
upon that of other members of the attack team. 
Few surface ships were available for training, 
and the sound gear was not of the most modern 
type during the early days of World War II. 
Still fewer target submarines could be pro- 
vided for school operations, and these were of 
the older types incapable of deep submergence 
or rapid maneuvering. Finally, the assessment 
of attack success presented the greatest difficul- 
ties. The method in general use was that de- 
scribed in Section 14.2, but its precision was 
not sufficiently great to determine whether or 
not the charges would have exploded within 


260 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


lethal range of the target. The training groups 
of the laboratories were able to make some 
contributions toward the solutions of these 
difficulties, but the sea phase of training con- 
tinued to be the most difficult one for the schools 
to conduct effectively. 

Antisubmarine Practice Targets 

The lack of submarines for school operations 
in 1942 was so serious that a request was re- 
ceived for the development and construction 
of synthetic practice targets which would sim- 
ulate the presence of a submarine to the at- 
tacking ship. The problem was studied in co- 
operation with the WCSS, and it was decided 
to attempt the development of a mobile elec- 
tronic target which would be essentially non- 
directional, return an echo of at least 2,000 yd, 
and exhibit doppler effect. 

The various forms of practice target that 
were designed all employed the telephone re- 
ceiver principle and consisted of a receiving 
transducer, amplifier, and transmitting trans- 
ducer. On receipt of the signal from the echo- 
ranging vessel, the impulse was amplified and 
returned to the water by way of the projector 
and subsequently picked up as an echo by the 
sonar gear aboard the attacking vessel. Filters 
were incorporated to reduce the effect of ex- 
traneous noise and the amplification adjusted 
below the point at which regeneration would 
set in. The first model was mounted on a raft 
towed by a small surface vessel, and in later 
modifications the transducers were mounted 
directly beneath the keel of this vessel with the 
electronic and monitoring equipment on board. 
Tests made in the harbor showed that when 
the projectors were submerged approximately 
6 ft deep, satisfactory echoes were obtained to 
2,500 yd. On the basis of this success, 37 raft 
and keel installations were constructed for use 
at the schools during 1942 and 1943. They con- 
tributed materially to alleviating the situation 
brought about by the shortage of submarine 
targets. 

Raft- and keel-mounted echo repeaters had 
certain shortcomings which were recognized 
early in their utilization by training activities. 
The small vessels involved could not operate 
satisfactorily under the various conditions en- 


countered at sea. The transducers were shallow 
and, in consequence, the range was short and 
the lost-contact range unrealistic. Also, the 
presence of the small vessel prevented the at- 
tacking ship from having complete freedom to 
maneuver in the neighborhood of the target. 
The first modification to attempt to meet some 
of these disadvantages was the buoy type of 
echo-repeater target which consisted essentially 
of the same transducer and electronic compo- 
nents, but in which the transducers were sus- 



Figure 9. Echo repeater practice target, model 

SR-2. Navy designation OAS. 

pended 50 to 100 ft beneath its surface by 
means of a cable supported by a small barrel 
buoy. The buoy target presented less of a 
hazard to the maneuvering of the attacking 
ship and the depth of the transducers provided 
adequate simulation of the depth of a subma- 
rine. This model, however, rested passively in 
the water and did not provide any doppler 
effect, but it was very economical in men and 
facilities and easy to keep in operation. Be- 
tween 30 and 40 of these were designed and 
furnished to the schools and other training ac- 
tivities during 1943. Eighty-three units were 
subsequently procured directly by the Navy. 

It had been recognized during these earlier 
developments that the eventual practice target 
should take the form of a towed, submerged 
body simulating more nearly the behavior of 
the maneuvering submarine. Work was under- 
taken in the autumn of 1942 on the develop- 
ment of such a target, and early in 1943, the 
SR-2 type shown in Figure 9 was developed. 
This consisted of a 330-lb torpedo-like body, 
containing the electronic amplifier and carrying 
two Rochelle salt crystal transducers in the 


ANTISUBMARINE WARFARE SONAR TRAINING DEVICES 


tail fins. A pressure-indicating unit was also 
included for depth indication. The transducers, 
which were identical with those used in the 
buoy model, were essentially nondirectional in 
the horizontal plane, thus making the target 
equally satisfactory for all bearings. The excess 
buoyancy of the unit was such that the target 
floated when at rest, but when towed at from 
4 to 6 knots at the end of a 1,200-ft cable, it 
ran at a depth of from 60 to 90 ft. The towing 
cable had an insulated electrical conductor as 
its core and power was supplied through this 
conductor from the towing boat. A separate 
portable unit, including the power supply and 
remote control panel, was carried in and con- 
trolled from this boat. The operator had the 
gain at his disposal and was able to monitor 
the signals that were received and the depth 
at which the target ran. This type of target 
was first put in use by WCSS early in 1943 and 
after a few months of use was considered suf- 
ficiently practical and satisfactory to warrant 
procurement on a considerable scale for train- 
ing activities. Good echoes were received at 
ranges as great as 4,600 yd in 600-fathom 
water and the laboratory constructed 16 units 
with successive refinements during 1943. One 
hundred and sixty-three units were later pro- 
cured directly by the Navy. 

The SR-2 was somewhat heavy for convenient 
handling, and before the practice target project 
was discontinued, a radical departure was made 
in the design of the SR-5. In this case, the body 
was a hollow, wing-type structure with excel- 
lent towing characteristics, and a total weight 
of approximately 100 lb. It was first tested in 
the autumn of 1943 at WCSS, and subsequently 
16 of these devices were made by the laboratory 
and furnished to training activities. It was 
much easier to handle than the SR-2, but in 
other ways performed identically. 

Evaluation of Attack Success 

Although the determination of whether or 
not a practice attack had culminated in the 
successful delivery of the depth charge or other 
projectiles was most essential in training ex- 
ercises, the problem presented in securing this 
information was never satisfactorily solved. 
Early in 1942, the problem of devising suitable 


equipment for this purpose was assigned to a 
contractor and, after an extensive period of 
development and test, certain units were pro- 
cured by the Navy. The equipment consisted 
essentially of a hydrophone carried by the tar- 
get submarine which recorded the acoustic im- 
pulse emitted by a small explosive cap thrown 
ahead by the attacking vessel. This cap was 
carried in a small body so shaped and weighted 
as to fall at a predetermined rate correspond- 
ing to the ordnance presumed to be in use. It 
was detonated by a pressure-actuated mech- 
anism. The electronic equipment aboard the 
submarine utilized the acoustic signal produced 
by the cap to display on dials the range and 
bearing of this small explosion relative to the 
conning tower of the submarine. The range was 
inferred from the intensity of the impulse and 
was dependent for its precision on the uniform- 
ity of the explosive caps. This uniformity was 
found to be adequate for the purpose. The 
bearing was determined by the ratio of the 
responses of two crossed velocity hydrophones 
and adequate precision was secured. The equip- 
ment received some operational testing at the 
schools, Pearl Harbor, and certain other bases 
and it appeared to be adequate for the evalua- 
tion of attack success to a precision commen- 
surate with the lethal range of ASW ordnance. 
The chief impediment to its effective employ- 
ment was the difficulty in installing it on the 
various submarines available from day to day 
for school operations. Extensive upkeep periods 
were necessary on these older types of vessels 
and frequently other assignments diverted them 
from school operations. The electronic equip- 
ment was complex and not available in suffi- 
cient quantities to equip all of the submarines 
that might from time to time be called upon to 
serve as targets, and it was infeasible to re- 
move and install the equipment during the brief 
interval available subsequent to the assignment 
of a particular vessel for school maneuvers. 

An essentially similar device was developed 
independently by a Navy laboratory which 
depended for range determination on the in- 
terval between the arrival of the light and 
sound from a small underwater explosion. Cer- 
tain difficulties were encountered in the pro- 
duction of satisfactory charges for this device, 


262 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


but it also promised to meet the need for an 
accurate evaluation of ASW attacks. 

In addition to the vegetable-crate water-slug 
method originally employed by the school, a 
photographic method was in use through 1943 
and 1944 for evaluating the success of ahead- 
thrown attacks. The maneuvering submarine 
towed a buoy float at the end of a line that was 
as short as was permissible and the location 
of this buoy with respect to the submerged 
submarine could be inferred with a satisfac- 
tory degree of precision. The procedure was 
then to photograph from the crows’ nest of the 
attacking vessel the splashes made by the entry 


■ate — ' *-** "*&. 



Figure 10. Shipboard antisubmarine attack 
teacher, model V. Model IV, Navy designation 
QFK, was very similar in appearance. 

of the ahead-thrown projectiles into the water, 
and if there was any possibility of the attack 
being successful, the buoy would also appear 
on the photograph. Careful subsequent meas- 
urements of the picture and a knowledge of 
the preceding maneuvers enabled the instructor 
to assess the success with which the attack had 
been made. Occasionally some difficulty was en- 
countered in securing satisfactory photographs 
under adverse weather and sea conditions but 
in general the procedure was found to be of 
great value. It had the drawback that the suc- 
cess of the attack could not be known until 
the photograph had been developed and studied 
and in consequence some training value was 


lost. It did provide a quantitative check, how- 
ever, on the performance of the teams under 
training, and it was of the greatest value in 
assessing the sea phase of operations. 

Shipboard Antisubmarine Attack 
Teacher [SASAT] 

It had been recognized in the earliest work 
in antisubmarine operations that the mainte- 
nance of a state of training represented one of 
the most serious problems of a commanding 
officer of an ASW vessel. Skills involved in an 
attack could be lost during the long periods of 
Navy assignment during which there were few 
opportunities to work with either submarines 
or practice targets. A shipboard device was 
needed which would permit the conduct of sim- 
ulated ASW drill and which would also enable 
the commanding officer to give shipboard train- 
ing to prospective sonar operators. Early in 
1943, the commanding officer of the USS Mc- 
Lanahan visited one of the division’s labora- 
tories and outlined his proposal for the type 
of device he would like to have aboard his 
vessel. Within two weeks the electronic com- 
ponents were designed and assembled in a small 
cabinet and given a trial on this vessel. Many 
inadequacies were brought to light but the 
original installation continued in use by the 
vessel. Subsequently a project for the design 
and development of a shipboard antisubmarine 
attack teacher was undertaken, resulting in a 
series of successive models approaching more 
closely the desired type of equipment. 

The only model that was procured to any 
extent during World War II was known as 
SASAT A, Navy designation QFK. Thirty units 
were built during the winter of 1943-44, and 
subsequently 100 units were procured under 
direct Navy contract. The instrument, which is 
shown in Figure 10, injected an echo into the 
standard sonar gear of such a character and 
at such a time as to conform to the echo that 
would have been received from a maneuvering 
target-submarine during a real attack. A range 
dial on the instrument controlled the time in- 
terval between the emission of a signal by the 
sonar gear and the receipt of the simulated 
echo. In order that the recorder trace should 
present a realistic slope, a range-rate dial auto- 


SUBMARINE SONAR SELECTION AND TRAINING 


263 


matically controlled the range dial in such a 
way that it increased or decreased at a rate 
appropriate to the maneuver. The echo length 
could also be controlled in such a way as to 
simulate the proper character for beam, bow, 
or stern attacks. The amplitude of the echo 
could similarly be controlled to simulate near 
or distant targets. The pitch of the echo was 
controlled by a doppler dial, and concentric 
bearing dials enabled the instructor to indicate 
the course of the ship and set the relative 
bearing of the target. In addition, provisions 
were automatically made within the apparatus 
for increasing the target width as the range 
decreased, attenuating the echo with range and 
with the angular training of the sonar head. 
In the final model of this device, dual signals 
were generated to provide a realistic simula- 
tion of split projectors. Thus the device could 
be used with the range recorder, the BDI, and 
the attack predictor. 

The situation presented to the sonar operator 
by SASAT A was highly realistic and his 
equipment would respond to all the adjust- 
ments available to him. The controls available 
to the shipboard instructor were adequate to 
simulate at his will any maneuvers he wished 
to portray. However, the relative motion prob- 
lem, which he had to solve in order to present 
a completely realistic situation to the operator 
and officers, made considerable demands on his 
ability and dexterity. A circular slide rule to 
assist him in his work was designed and fur- 
nished with each equipment, but it was obvious 
that any final acceptable design should be more 
completely automatic in the generation of the 
problem. Instructor’s manuals were supplied 
with each equipment, and they not only con- 
tained directions for its operation but also 
provided tabular material which could be used 
by the instructor for the generating of typical 
runs. 

In addition to this device, a somewhat simi- 
lar piece of equipment known as the QFG was 
procured by the Navy. The design of this was 
based on the modified harbor defense trainer, 
but it proved somewhat less well adapted to 
shipboard work. 

In an effort to design a completely automatic 
attack teacher, one of the division’s labora- 


tories worked for a considerable period, at 
relatively low priority, on SASAT B. Certain 
progress was made toward the solution of the 
various problems presented by a completely 
automatic trainer, permitting freedom of ma- 
neuvering to the ship and providing an accurate 
record of the positions of the ship and synthetic 
target, but the device did not reach the stage 
of service tests and evaluation before personnel 
were diverted to more urgent assignments. 


SUBMARINE SONAR SELECTION 
AND TRAINING 


Opportunities for Assistance 

By the summer of 1943, the relative priority 
of the prosubmarine and antisubmarine efforts 
justified the diversion of considerable effort on 
the part of the division to the technical needs 
of the submarine service. A very small amount 
of training work had been done in association 
with the medical officer of the Submarine Base, 
New London, during 1942. At this activity cer- 
tain pioneer work had been undertaken in 
audiometry, and it was thought that this might 
have some bearing on ASW operator selection 
procedures. The problems, however, were found 
to be quite different, and although a minor pro- 
gram of assistance continued at the Submarine 
School, New London, no considerable assistance 
was rendered to that activity until the divi- 
sion’s interests as a whole were oriented toward 
submarine problems. In spite of the active par- 
ticipation of the division’s contractors in anti- 
submarine work during the preceding years, 
little was known about the organization of the 
submarine service or its technical requirements. 
In consequence, considerable time was required 
in the summer of 1943 to acquaint the division 
as a whole and the training committee and 
training groups of the contractors in particular 
with the organization of the submarine service 
in order that the proper contacts could be estab- 
lished and opportunities for the rendering of 
assistance developed. 

Elementary training in all phases of subma- 
rine operation was centered at the Submarine 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


School at New London, which was a shore- 
based establishment under the direction of the 
Bureau of Personnel. It operated closely with 
ComSubLant and his staff, which by their prox- 
imity and intimate association determined the 
general nature of the curricula offered. This 
was in distinction to the ASW schools for which 
the Readiness Division of COMINCH and later 
the Tenth Fleet performed an analogous func- 
tion. The major Navy training establishment, 
at which operational training and evaluation 
were conducted, was at Pearl Harbor under the 
command of ComSubPac. 

The geographic separation between New Lon- 
don and Pearl Harbor rendered the free and 
frequent interchange of ideas and personnel a 
matter of considerable difficulty. The Subma- 
rine School, partially by the nature of the ex- 
igencies of this service, was somewhat insular 
and, in consequence, less familiar with the re- 
cent developments in sonar training at the 
large and newly established surface schools. 
The principal Navy training command was not 
only remote but also lacked liaison with the 
sound schools. The geographic situation was 
likewise a handicap to the laboratory groups 
working on assignment at Pearl Harbor, and 
had prevision been available, the division might 
well have established a laboratory at that loca- 
tion much earlier in World War II. The sub- 
marine force, however, was composed of eager, 
aggressive officers with an experimental out- 
look and ingenuity in extemporizing, and these 
characteristics went far to alleviate the handi- 
caps imposed by the geographic separation be- 
tween Pearl Harbor and the development lab- 
oratories. 

Sonar techniques are of particular importance 
to the submarine because when submerged it is 
dependent upon them almost exclusively for 
the receipt of information. A wide variety of 
sonar aids can be utilized in the various ma- 
neuvers of exploration, approach, attack, and 
evasion. The technical developments that took 
place concurrently with the establishment of 
training programs and the improvement of 
training methods were more considerable than 
in the case of ASW, and in consequence a 
larger fraction of the training effort was de- 
voted to training in the use of new gear. Secrecy 


and security are a prime concern to a subma- 
rine; hence emphasis was placed on listening 
rather than on echo ranging. In later develop- 
ments of submarine sonar gear, including the 
fathometer, power levels, frequencies, and 
beam patterns were carefully considered from 
the point of view of security, and this consider- 
ation was emphasized in all training programs 
involving the use of gear emitting sonic or 
supersonic sounds. A further significant differ- 
ence between the work with submarines and 
with surface ships was the smaller number of 
the former. In consequence, more effective as- 
sistance could be rendered by the laboratories 
in the construction of limited numbers of de- 
vices and in pilot procurement through subcon- 
tractors. 

The smaller number of submarine personnel 
made it somewhat easier to provide training 
facilities and the higher degree of training and 
skill commonly encountered aboard submarines 
provided a broader basis upon which special 
training programs could be erected. Except for 
the operations in the Pacific, the proximity of 
the division’s laboratories to naval training ac- 
tivities was again a favorable factor in the es- 
tablishment of close relationships and the ren- 
dering of assistance. The New London labora- 
tory was adjacent to the Submarine School and 
the training activities of ComSubLant. The 
training group at that laboratory was able to 
render effective aid in many branches of sonar 
training as well as in fields quite remote from 
underwater sound. 

At a meeting of a naval board attended by 
civilian training assistants in July 1944, it was 
recommended that submarine sonar training be 
transferred to WCSS in order to take advan- 
tage of the extensive experience gained by that 
establishment in ASW training and the special 
devices and experienced instructors there avail- 
able. In conformity with this recommendation, 
the sonar training program was transferred in 
the autumn of 1944, and the proximity of the 
San Diego laboratory again presented a very 
favorable opportunity for close collaboration 
and assistance. The proximity of that labora- 
tory to squadrons of the Pacific Fleet was also 
found to be of the greatest value in gaining fa- 
miliarity with the requirements of the subma- 


SUBMARINE SONAR SELECTION AND TRAINING 


265 


2500 


2000 


o 1500 


! 1000 


500 


100 


7 5 


Vi 

z 
o 

50 


25 




CUMULATIVE TOTALS 
SUBMARINES AND 




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1 — 

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CUMULATIV 

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INSTALL 

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: SONAR 
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FlGu f The above charts show for submarines what Figure 1 illustrated in relation to surface 
vessels. The noteworthy increase in trained enlisted sonar men is shown, the curves used being reasonable 
interpretations of figures made available by the Submarine School, New London, and the U. S. Fleet 
Sonar School, San Diego. The improvement in quality of training as experience in this field was gained, 
further increased the effectiveness of the sonar complements. 

The figures on the total submarines and sonar installations were made available through the excellent 
cooperation of Code 5815, BuShips. The introduction of the combination sonic-supersonic listening gear 
is indicated in the growth of the JP and JT curves (JK gear was supersonic only). The remaining curves 
for standard echo-ranging gear (except QLA, which later was frequency-modulated PPI gear) indicate 
the increase and decrease of the various types throughout World War if. 

It is noted that until 1942 most of the submarines in service were 0, R, and S boats, whereas sub- 
sequently fleet-type vessels largely undertook the combat patrols. 



266 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


rine service and in maintaining close relations 
with its training activities. Training assistants 
from the division’s laboratories were assigned 
to Pearl Harbor and advanced bases and ren- 
dered as effective aid as they could under the 
handicaps of remoteness and difficulties of com- 
munication and transportation. The observa- 
tion of the laboratories’ activities in the sub- 
marine training field re-emphasized the great 
advantages that result from close proximity. 


1482 Submarine Training Program 

During 1944 and 1945, the laboratories of the 
division devoted extensive efforts to the assist- 
ance of submarine sonar training activities. 
This assistance took many forms but roughly 
paralleled the type of work performed in the 
ASW program. In consequence, it will not be de- 
scribed in such great detail, but representative 
activities will be considered, with particular 
emphasis on those aspects which presented 
problems that were not common to the ASW 
program. 

The submarine sonar operator’s job differs 
from that of the surface vessel operator both in 
the gear used and in the conditions under which 
operation takes place. The need for a special 
submarine sonar operator’s manual was early 
apparent, and on receipt of a request for it, a 
standard handbook on the operation of all types 
of sonar gear was prepared. The manuscript 
was completed in September 1944, and 5,000 
copies were issued by the Bureau of Personnel 
and distributed to the submarine service. 

Assistance was rendered to the new-construc- 
tion submarine training program at New Lon- 
don through the development of a two-week 
sonar operator’s course. The first week covered 
lectures and operation of equipment on pier in- 
stallations. The second week, on the sonar- 
radar barge, was devoted to the operation of 
equipment. A four-week course for submarine 
sonar materiel men was outlined in collabora- 
tion, with the instructors of the sonar materiel 
course at the Submarine School, and assistance 
was also given in the preparation of material 
for lectures and laboratory exercises. On the 
receipt of advice that the sonar training pro- 


gram would be transferred to WCSS, the lab- 
oratories concentrated on cooperating with 
that activity in the devising of curricula, lec- 
tures, demonstrations, laboratory exercises, 
and training devices. By the autumn of 1944, 
the training program was ready to be placed 
in operation, and the laboratories continued to 
study the effectiveness of the training methods, 
introducing new techniques, and modifying the 
training equipment as inadequacies became ap- 
parent. 

The laboratories assisted in the design of 
sound training barges at New London, San 
Diego, and Pearl Harbor. These were equipped 
with a large number and variety of sonar gears 
appropriate to submarine installation and also 
contained radar and radio equipment. Excellent 
training could be given on them not only in 
sonar operation but in integrated sonar-radar 
training. At Pearl Harbor, training assistants 
worked with personnel officers in classification, 
selection, and training, also in studies and sta- 
tistical analyses of personnel records. This in- 
formational background was used for the estab- 
lishment of entrance standards for the training 
command courses in order that the training 
facilities could be used to the best advantage. 
A preliminary survey of the auditory capabili- 
ties of the prospective sonar men was carried 
out in an effort to develop suitable criteria for 
sound discrimination ability. This work was 
continued and amplified by the training group 
working at WCSS and contributed markedly 
to the eventual success of the enlarged sonar 
training program. 

Submarine Sonar Training Devices 

A large number of submarine sonar training 
devices were developed but many of these 
closely resembled analogous equipment previ- 
ously in use by the schools. The primary listen- 
ing teacher, Navy designation QFF, resembled 
closely the primary bearing teacher and dif- 
fered only in the presentation of screw sounds 
in place of echoes. Similarly, the advanced 
listening teacher bore a close resemblance to 
the advanced bearing teacher. The added ex- 
perience gained by the laboratories in the de- 
sign of such equipment, however, enabled the 
production of a more highly refined instruc- 


SUBMARINE SONAR SELECTION AND TRAINING 


267 


tional device. Submarine conning officer attack 
teachers were modified to include a sound injec- 
tor for the purpose of providing target noise 
at the proper sound level and correct bearing. 
Similarly, a few sound injectors were built and 
furnished submarines for use in refresher 
training and practice. The need for this type of 
device is somewhat less with the submarine 
than with the ASW vessel since targets are 
encountered more frequently by the submarine 



Figure 12. Sound recognition group trainer, as 
installed at the U. S. Fleet Sonar School, San 
Diego. The recorders, console, and turntable are 
seen at the lower right, and some of the students’ 
stations can be seen at the left. 

and a greater opportunity for realistic practice 
is thereby presented. 

Sound Recognition Group Trainer [SRGT] 

Profiting by the experience in ASW work 
with WCSS, it was recognized that realistic 
group trainers would be of maximum effective- 
ness in the expanded submarine sonar training 
program in contemplation in 1943. In conse- 
quence, the design of two new modern group 
trainers was undertaken for this program, and 
in many ways they represent the culmination of 
design experience in the field of training de- 
vices. One of these was the sound recognition 
group trainer for the provision of closely 
guided instruction in the recognition and inter- 
pretation of sounds heard over submarine sonar 
equipment. It resembles the echo recognition 
group trainer in that it consists of a phono- 
graph turntable and central recorder console, 
together with a plurality of student stations. 


Twenty stations were provided in the units of 
the SRGT that were built and installed in sub- 
marine training activities. Two units were em- 
ployed at the West Coast Sound School and one 
at the Submarine School, New London. 

In this trainer, an editqd and graded series 
of sea recordings is presented to the class and 
students register their judgment on the selec- 
tion to which they listen. In order that a va- 
riety of operating conditions may be simulated, 
the output of the phonograph pickup can be 
presented either through a standard JP or 
standard WCA receiver or, at the option of the 
instructor, through an amplifier having a flat 
frequency response from 60 to 10,000 c. The 
student's judgments appear as two-digit num- 
bers on the paper of a monitor recorder at the 
instructor's position. Each student listens 
through headphones and indicates his judg- 
ment by depressing one of 70 appropriately 
labeled pushbuttons at his station. When a 
pushbutton at a student’s station is depressed, 
a two-digit number appears in facsimile in the 
column on the recorder paper assigned to that 
particular station. Each monitor recorder pre- 
sents eleven columns, ten for students and one 
for the instructor. Some of the phonograph re- 
cordings include 40- or 70-c tones which are 
made inaudible to the students by means of 
suitable filters. These tones automatically actu- 
ate the instructor's styli on the monitor re- 
corder to indicate the presence of certain tar- 
get sounds, thus providing a standard with 
which the student's judgments can be com- 
pared. These tones are also used for operating 
a range-indicating device during single-ping 
ranging drills. A microphone and amplifier are 
provided in order that the instructor may com- 
municate with the students while they are 
wearing their headphones. The illustration in- 
dicates the arrangement of the equipment in a 
classroom. Numerous controls are provided for 
adjusting the sound level, the choice of ampli- 
fier characteristics, and the insertion of filters. 

Group Listening Teacher 

The second modern group instructional de- 
vice for submarine sonar training was devel- 
oped from the advanced listening teacher. This 
trainer bears a resemblance to the group op- 


268 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


erator trainer in that the student is presented 
with actual sonar gear and the problem is de- 
veloped and sounds generated automatically by 
a central console to which the stacks are con- 
nected. The group listening teacher gives si- 
multaneous instruction to a number of operators 
on different types of equipment. Model CXKG 
is for the training of groups of students in 
listening techniques on WCA and JT equip- 
ment. Model CXKG-1 is for training on WFA 
sonar equipment. Under pressure, an interim 
model with no Navy designation was designed 
and built in a period of about 6 weeks to ac- 



Figure 13. Group listening teacher console. 

commodate the first submarine sonar class at 
WCSS in November 1944. The master station 
of that unit consisted of an adapted advanced 
listening teacher and the student stations orig- 
inally consisted of JP, WCA, and WEB sound 
stacks. The revised and improved models of the 
CXKG series were undertaken in December 
1944 and were not entirely complete before the 
transfer of the program to Navy auspices. 

The WCA half of the CXKG was, however, 
complete, and it is representative of the other 
models of this equipment, consisting of a master 
station shown in the illustration (Fig. 14) and 
five duplicate student stations housed in small 
booths grouped around the master console. The 
instructor sits at the latter and can monitor 
the performance of students through the glass 
doors of the booths. The master station gener- 


ates sounds to simulate two surface vessels and 
a submarine, in addition to appropriate water 
noises. The instructional material is provided 
in the form of three 20-minute runs which 
range in difficulty from elementary to advanced 
situations. Two of the runs are concerned with 
attack situations in which torpedoes are fired. 
A third run presents the problem of evasion in 
which the submarine maneuvers to escape from 
two ASW vessels and successfully eludes attack. 
A fast reset control is included so that the in- 
structor can select or repeat any particular part 
of a problem for concentrated drill. Provision 
is made for the simulated firing of torpedoes to 
give training in a sound attack. The master sta- 
tion contains a cam control, mechanical prob- 
lem generator, and various electronic circuits 
for sound effects, control, and monitoring. The 
student stations consist of standard WCA 
stacks adapted for use in the trainer. 

JP Listening Equipment 

The introduction of JP listening equipment 
required the assistance of the laboratories in 
the provision of introductory and training 
equipment. A complete course of instruction in 
this device was provided and a set of training 
aids was prepared in connection with it. These 
included demonstration material on amplifiers 
and miscellaneous parts, visual aids, such as 
lantern slides and slide films, and also hand- 
books and pamphlets for instructors and opera- 
tors. Phonograph recordings were also pre- 
pared and an enlarged JP amplifier mockup 
was provided for the submarine school. Train- 
ing kits were furnished to the principal sub- 
marine training activities at New London, 
Portsmouth, Manitowac, Key West, San Diego, 
Hunter’s Point, Pearl Harbor, Midway, and 
Subic Bay. Training assistants visited most of 
these activities and assisted in the inauguration 
of training programs, participating frequently 
in the lectures and demonstrations until naval 
personnel were sufficiently acquainted with the 
gear to take over the instruction. 

FM Sonar [QLA] 

With the advent of QLA installations, need 
for similar training assistance became appar- 
ent. As these installations were made in the 


SUBMARINE SONAR SELECTION AND TRAINING 


Pacific, this training program was concentrated 
in that area. One phase of this activity was the 
training of materiel and maintenance men in 
the laboratory. Classes of six or eight at a time 
were assigned, beginning in the early spring 
of 1945, and were given a 6 weeks’ course in 


erator instruction occupied three days of the 
submarine sonar training curriculum at the 
WCSS. A moving picture film was prepared by 
the laboratory and used both at the school and 
at advanced bases to introduce the operator to 
this new type of sonar gear. An instruction 



Figure 14. Group listening teacher. Left, a representative WCA stack for students. Right, a view 
of the room in which the teacher was housed at the U. S. Fleet Sonar School, San Diego. The rear of the 
console can be seen at the right. It was surrounded by booths housing students’ stations. 


maintenance and operation. This activity con- 
tinued after the transfer of the program to 
Navy sponsorship. Maintenance manuals were 
prepared and instructions given in the labora- 
tory, afloat on laboratory vessels, and on QLA- 
equipped submarines assigned to the area. Op- 


manual was prepared and furnished the school, 
and the design of an electronic trainer was un- 
dertaken and later completed under Navy 
auspices. The introduction of and training in 
this device were also carried on by engineers 
and training assistants at bases in the Central 



270 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


Pacific, utilizing the training material prepared 
by the laboratory for use there and at the 
school. 

Noise Level Monitor [NLM] 

The noise level monitor was another device 
requiring assistance in operational training. A 
brief lecture course and auxiliary slides and 
charts were prepared at the laboratory to pro- 



Figure 15. Noise level monitor trainer. 

vide actual operator training in reading and 
recording NLM measurements. A NLM trainer 
was designed for use at major training activi- 
ties. This trainer permitted two sources of re- 
corded sounds to be fed into a single NLM unit, 
thus simulating the effect of background noise 
with auxiliary noise superimposed upon it. 

Torpedo Detection Modification [TDM] 

The torpedo detection modification of stand- 
ard gear also involved a training problem. Lec- 
ture outlines covering operation and mainte- 
nance, together with suitable slides and an op- 
erator's manual, were prepared by the labora- 
tory. A slight modification of the QFL (tac- 
tical range recorder teacher) made it possible 
to use this training device for teaching TDM 
operation. A series of records of torpedo runs 
was made for use with this trainer. 

NAD Beacons 

The NAD beacons may also be considered as 
directly related to sonar gear, and their intro- 
duction involved an extensive materiel training 
program and participation in operational train- 


ing and tests. A series of classes was assigned 
by SubTrainPac to the laboratory for training 
in maintenance and upkeep. The instruction 
period averaged 6 weeks, and covered all as- 
pects of beacon testing, repair, and operation. 
Manuals were prepared for these students, and 
lectures were formulated and delivered by lab- 
oratory personnel. 

Bathythermograph Program 

The bathythermograph training program for 
submarines may also be considered under this 
same general heading. Prosubmarine instruc- 
tion in this device began in a small way on the 
east coast as part of the study of the submarine 
model BT as an aid to diving. As each subma- 
rine was fitted with the BT, a member of the 
laboratory staff was sent to adjust it and de- 
termine the compressibility of that particular 
vessel. Opportunity was thus afforded for indi- 
vidual training by these representatives. As 
the three persons engaged in this early work 
became acquainted with the submarine service, 
it became easier to find opportunities for more 
formal instruction. On returning to the base 
after a cruise, a group of officers would be as- 
sembled and a class would be held. It was 
gradually recognized that such instruction 
should be formalized and given to all submarine 
officers, and requests were received for the es- 
tablishment of a series of lectures for groups in 
training at the Submarine School. Early in 
1944, a request to expand this program was re- 
ceived, and a special BT training group was 
assembled to concern itself with training in- 
volving the BT on both surface and submarine 
vessels. 

In view of the greater importance of this de- 
vice to the submarine, emphasis was placed on 
the submarine phase of the work, and three 
types of activity were undertaken. The first of 
these was the training of submarine BT pilot 
instructors to be assigned to Atlantic and Pa- 
cific submarine commands for improving the 
effective utilization of the BT. A group of 6 or 
8 men was trained, and at one time or another 
most of them participated in work with sub- 
marine training activities. The work of these 
instructors centered largely at New London 
and Pearl Harbor but from time to time they 


RELATED TRAINING PROGRAMS AND DEVICES 


271 


visited a large number of advanced bases. They 
were particularly helpful in the introduction of 
training aids and literature and in general in- 
struction in subsurface oceanography, inter- 
preting range charts, bottom sediment charts, 
and submarine supplements to the sailing direc- 
tions, as these were issued by the Navy and 
reached the submarine commands. 

Other training aids were also designed and 
constructed by the laboratories. Some of these 
were merely lecture demonstration kits, but a 
more considerable piece of equipment was the 
BT adjunct to the Askania diving trainer. This 
was an optical and electronic device which, on 
the insertion of a BT card into a receptacle, 
would bring about the proper reaction of dials 
and controls to the inhomogeneity of the sur- 
face layers represented by the BT trace. Only 
one unit of this equipment was constructed and 
it was used at both San Diego and Pearl Har- 
bor. A similar modification was later made in 
the standard diving trainer as procured by the 
Navy. 

A third phase of the BT training program 
was the provision of manuals and other train- 
ing aids by laboratory groups. In general, this 
material was assembled and edited and the 
necessary illustrations drawn and dummies 
prepared for submission to the Bureau of Ships 
for approval. They were reproduced by offset 
lithography in color and issued to the Navy. 
The first of these manuals was entitled, Work- 
book for the Prediction of Maximum Echo 
Ranges, NavShips 900,050. This included the 
most recent information available on the pre- 
diction of maximum echo ranges, the reading 
of BT slides, the utilization of sound ranging 
charts, and the preparation and sending of the 
sonar message. The second manual was en- 
titled, Herald Ranges, NavShips 900,070. It was 
prepared specifically for harbor defense officers 
and other personnel concerned with the de- 
sign, operation, and location of harbor defense 
gear. The manual discussed effect of oceano- 
graphic factors on the operation and location of 
harbor echo-ranging and listening devices. The 
largest undertaking in this field was the prepa- 
ration of Use of Submarine Bathythermograph 
Observations, NavShips 900,069. This manual 
was prepared for submarine officers and en- 


listed men concerned with sonar gear and div- 
ing. It presented a comprehensive survey of the 
effect of oceanographic factors on sound condi- 
tions and on the operation of submarines. It 
also discussed the uses of the submarine BT 
as an aid in predicting sonar conditions and 
ballast adjustments, and covered the tactical 
implications of such information. The manual 
represented very careful thought in organiza- 
tion and preparation on the part of both the 
contractor and the bureau. A number of other 
manuals were projected but not completed be- 
fore the summer of 1945. 

A further unofficial publication to aid the 
pilot instructors and other technical personnel 
associated with the BT was the Manual for BT 
Pilot Instructors, distributed in 1945. 

Finally, this group prepared a BT Slide Kit, 
NavShips 900,083, to give additional instruction 
to sonar officers and sonar men in the reading 
and interpretation of BT traces. It consisted of 
photographic reproductions of ten varied but 
typical BT slides chosen from a collection of 
over 30,000 ; a booklet of instructions, ques- 
tions, and answers; and a viewer and special 
grid for reading the slides. 

149 RELATED TRAINING PROGRAMS 
AND DEVICES 

The major attention of the training commit- 
tee of the division and the training groups of 
the contractors was given to antisubmarine 
warfare during the first years of World War 
II and to prosubmarine sonar devices during 
the latter period. The official field of the division 
was somewhat broader, including as it did all 
phases of subsurface warfare, and some train- 
ing projects extended into fields somewhat re- 
mote from sonar. In the case of certain radar 
training assistance and development in the field 
of CIC training, the extension was actually be- 
yond the field of subsurface warfare. Such pro- 
grams in which instruction material was pre- 
pared or extensive participation occurred are 
briefly described. 

Radar Operator’s Course 

Assistance in the development of a basic 
radar operator’s course at the New London 


272 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


Submarine School was undertaken in October 
1944, by a training group. The Applied Psy- 
chology Panel, NDRC, collaborated in this 
work. Assistance was furnished in planning 
laboratory and classroom facilities, and in out- 
lining a 2 weeks’ training course. Instruction 
material was prepared, and examinations of 
both written and practical types were designed 
and introduced. 

Submarine Interior Communications 
Training Program 

A request was received from ComSubLant 
for assistance in the training of telephone talk- 
ers, since the problem of interior communica- 
tion had proved to be one of considerable im- 
portance and special difficulty. Work had been 
done by other NDRC groups on interior com- 
munications in aircraft, and at a conference in 
New London, representatives of the Harvard 
Psycho-Acoustic Laboratory, the Applied Psy- 
chology Panel, the contractors’ training groups, 
and naval liaison met to determine what as- 
sistance could be rendered the submarine force 
in this field. Men were furnished by the other 
NDRC activities, and the division’s laboratory 
acted to coordinate the activities of all groups 
interested in submarine interior communica- 
tions and to maintain liaison with the Navy. 

The program fell under two headings: (a) 
the analysis and standardization of interior 
communications, procedures, and phraseology; 
(b) the establishment of a training course for 
personnel using interior-communications equip- 
ment. Lists of standard commands were col- 
lected and tested for intelligibility, procedures 
were reviewed and corrected, and a basic 4- 
hour course was developed and tested with 
classes of submarine officers and men. Later the 
interior-communications training program was 
extended to include the Submarine Schobl. 

A U. S. Fleet Telephone Talker's Manual, 
Submarine Edition, and a chapter on interior 
communications for the ship’s organization 
booklet were prepared. A glossary of standard 
submarine phraseology was also assembled, as 
was a pamphlet of standard submarine com- 
munications procedures. Recordings and in- 
structional manuals for the submarine tele- 
phone talker’s training course were also fur- 


nished. This doctrinal and training material 
was likewise furnished to advanced bases where 
communications instruction was given, and 
training officers were coached in its use. 

Periscope Attack Trainers 

In several instances the training groups and 
development laboratories assisted in the design 
and production of training devices giving both 
shore and shipboard practice in periscope at- 
tacks. The principal device in this field was the 
periscope range trainer (see Figure 16) which 
was a device to be used ashore for instructing 
submarine personnel in the use of the peri- 
scope. By means of this trainer, practice could 
be given in the identification of targets and the 
determination of their range and aspect. Six 
units of this device were completed in April 
1944 by one of the laboratories, and consulting 
services were furnished in connection with the 
subsequent production order for 25 by the 
Navy. This device gave valuable shore train- 
ing in the use of the periscope, and the models 
constructed by the laboratory were installed at 
New London, Portsmouth, Mare Island, Mid- 
way, and Pearl Harbor. 

In addition to the periscope range trainer, a 
request was received to assist in the much- 
needed modernization of a few strategically lo- 
cated installations of the basic shore-based 
training device known as the submarine con- 
ning officer attack teacher. This trainer was de- 
signed shortly after World War I. In it, single 
targets were moved manually along the track 
and the attack problems that could be presented 
were far from realistic. Redesigning involved 
the construction of a new carriage for the 
target and an auxiliary control cabinet operat- 
ing with a modified Mark I TDC. Target and 
screen ships, as well as the car and conning 
tower, and another repeater unit in the class- 
room showed the relative bearing, target speed, 
range, and angle-on-the-bow for the instruc- 
tor’s information. With the modifications thus 
introduced, a target ship and 7 screen ships, or 
5 target ships, or any combination within these 
numeric limits could be portrayed. Manual con- 
trol of the screen ships and lighting could be 
effected through an auxiliary control cabinet. 
Seven of these modification units were con- 


RELATED TRAINING PROGRAMS AND DEVICES 


273 


structed by the laboratory and distributed to 
New London, Portsmouth, Mare Island, Pearl 
Harbor, Midway, and Subic Bay. 

In addition to the shore-based periscope 
trainers, a proposal for the construction of a 
shipboard periscope attack teacher emerged as 
a result of conferences at Pearl Harbor in the 
autumn of 1943. Long submarine patrols af- 
forded occasions during which practice could 
be obtained in the conduct of periscope attacks 


ent frames during periods of occultation. The 
lighting effects would be chosen by the instruc- 
tor to suit the problem being presented. Varia- 
tion in range and true and relative bearing 
would be brought about automatically in re- 
sponse to simulated ship controls by mechanical 
means and the various motions so integrated as 
to present on dials at the side of the instrument 
the actual range bearing and bow angle in 
order that the progress of the attack could be 



Figure 16 . Periscope range trainer. Left , the trainer. Right, a representative field of view as seen in 


if a sufficiently realistic and compact device 
could be supplied to each vessel. The combina- 
tion of realism, accuracy, and compactness pre- 
sented a difficult design problem, but work on 
this device was undertaken by one of the lab- 
oratories early in 1944. An observer would be 
presented with a realistic field of view through 
an orifice at approximately eye level and pro- 
vided with controls simulating those of peri- 
scope operation. Various ship types could be 
presented as images on a film, the angle-on-the- 
bow being varied by the substitution of differ- 


recorded and its success evaluated. In the late 
spring of 1944, this NDRC project was discon- 
tinued and the design information furnished a 
Navy supplier. 

CIC Trainer 

In the autumn of 1943, the chairman of the 
Selection and Training Committee visited the 
submarine and destroyer commands at Pearl 
Harbor for the purpose of determining how the 
previous training work of the division could be 
directed more effectively toward the solution of 



274 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


problems encountered by the Pacific Fleet. The 
relative infrequency of encounters with Jap- 
anese submarines rendered ASW training of 
lower priority than training in surface and 
antiaircraft actions. At the request of ComDes- 
Pac, conferences were held with the command- 



Figure 17. CIC trainer and display system, as 
installed at COTCPac, San Diego. The upper 
picture shows the rear of the projectors and the 
control central at the right, in the background 
are some of the conning and fire control stations, 
and at the left is an SG radar receiver on top of 
the panel containing the pickup scope and other 
electronic components of the trainer. The lower 
picture shows the front of the projectors as seen 
from the screen and some conning stations. The 
monitoring radar may be seen at the right. The 
CIC room with DRT and radar repeater as well 
as the principal conning station were in rooms 
directly beneath that shown in the figures. 

ing officer at the Pacific Fleet Radar Center, 
which was at that time engaged in the develop- 
ment of methods for the more effective integra- 
tion and utilization of radar and other infor- 
mation in the conduct of surface and antiair- 
craft actions. It was evident that an oppor- 
tunity existed for the furnishing of training 
assistance, and as a result of the discerning 


analysis presented by the officers of the Radar 
Center, general specifications were established 
for a trainer, and its immediate development 
was requested. The concept of the Combat In- 
formation Center was developing at that time 
under the pressure then existing for more ef- 
fective assimilation of available information 
aboard ship. The proposed device was called 
the CIC Trainer. 

The project was assigned to a contractor’s 
laboratory and the work was carried out in 
close association with the Operational Training 
Command of the Pacific Fleet which had its 
headquarters in the buildings of the WCSS. 
Following the recommendations that emerged 
from the initiating conferences with the de- 
stroyer command, the trainer was intended to 
fulfill two general purposes. The first was to 
facilitate and improve the training of the 
officers and men who composed CIC teams and, 
to a lesser extent, the training of associated 
officer specialists in torpedoes, gunnery, and 
navigation. The second purpose was one of dem- 
onstration and exposition, for displaying to ob- 
servers the conduct of a naval engagement under 
modern conditions. It was hoped that this not 
only would be of value to observing CIC teams 
and to senior officers in assessing trainees’ per- 
formance, but that it might also provide greater 
insight to group and force commanders in the 
tactical and strategic potentialities inherent in 
the scope, accuracy, and speed characterizing 
information obtained by radar. 

It was recognized that the training would be 
most effective if standard shipboard equipment 
were used by the CIC team. In consequence this 
principle was adopted, and the surroundings 
and radar presentation were made as realistic 
as possible. The problem of reconciling com- 
plexity and flexibility was met by the adoption 
of a unit principle in construction. In this way 
a trainer could be built up to the complexity 
required by the problems handled at a particu- 
lar training activity, without necessitating the 
provision of more extensive facilities than nec- 
essary at advanced bases or elementary train- 
ing centers. Following this principle, it was 
also possible to grade the exercises. Initially, 
simple problems calling only for standard pro- 
cedures could be presented in order to intro- 


CONCLUSION 


275 


duce junior or auxiliary personnel to elemen- 
tary maneuvers. In other applications, classical 
actions or situations could be initiated or re- 
produced in part with subsequent freedom of 
maneuver for one or more ships to provide 
demonstrations and intermediate training. In 
the more advanced stages, duels could be con- 
ducted between two CIC teams, starting with 
an arbitrary configuration of ships and per- 
mitting complete freedom of maneuver subject 
only to the limitations imposed by actual ship 
speeds and turning radii. Accurate records 
could be made of the developing action at all 
stages for subsequent analysis and evaluation. 
A final feature was the accuracy which was 
provided in the initial positioning of ship or 
plane units and in the generation of course and 
speed. Although it was recognized that actual 
maneuvers at sea were subject to many naviga- 
tional factors introducing uncertainty, plot- 
ting was an important phase of CIC training, 
and accuracy in the generation of the problem 
was essential for refined plotting and for the 
reproduction of maneuvers. 

The principal work in this general field was 
the construction, testing, and operation of an 
experimental model of this trainer installed at 
the WCSS and used by the CIC training group 
of COTCPac. This trainer controlled in a 
realistic manner the motion of eight optical 
projectors for displaying on a screen the ma- 
neuvers of ships and planes and presenting the 
resulting configurations to the CIC radar re- 
ceivers. A projector could be used to simulate a 
ship, a plane, or a torpedo, and in these various 
services the image was given an appropriate 
conventionalized form. The motion was brought 
about by the traversing of the projecting lens 
in a plane perpendicular to its axis. This mo- 
tion was controlled by a conning station having 
appropriate speed and turning parameters for 
the unit to be represented. In the case of a tor- 
pedo, the projector was moved as a slave to the 
ship in which the torpedo was loaded, and, on 
firing, it was liberated and assumed a pre- 
determined course, speed, and run. 

In the first installation, the SG radar alone 
was used, and in consequence it was only appro- 
priate for ships and low-flying planes to appear. 
The coordinates of the projecting lenses were 


integrated through a control central and, by 
means of auxiliary electronic equipment, pre- 
sented as potentials to the radar receivers in 
such a way that realistic presentations ap- 
peared on the scopes in response to the various 
controls. In addition to these features, which 
represent the most essential ones of the trainer, 
gun fire could be portrayed by means of slits 
and expanding diaphragms at the focal plane 
within a projector. Auxiliary sound effects were 
produced by battle recordings, and intercom- 
munication circuits between the various sta- 
tions provided the necessary realistic contact 
between participants in the problem. 

The trainer was used in a wide variety of 
ways but most extensively in the training of a 
single CIC team. In this application, the group 
commander conned his flagship, which resulted 
in the maneuvers of one of the projecting 
images. A record of these maneuvers was fur- 
nished automatically to the DRT, and the CIC 
received radar information on the location of 
all other targets in the area. By voice communi- 
cation, the group commander directed officers 
at other conning stations in the maneuvering 
of other vessels in the force. One or more 
enemy vessels were maneuvered from another 
conning station which could be supplied with 
appropriate radar information. Low-flying 
planes could be introduced at will by the officer 
in charge of the problem. Practice was also 
given in shore bombardment work by using one 
or more of the projector units as headlands or 
other readily recognizable radar targets. 

The equipment was used by COTCPac during 
the spring of 1945 and maintained in service 
by the laboratory staff. Some study of the train- 
ing afforded was made by the training group 
at the WCSS, and valuable experience was 
gained upon which the design of further pro- 
duction units was based. The construction of 
three additional units was undertaken under 
NDRC auspices but not completed before the 
contract under which the laboratory operated 
was assigned to the Navy. 

1410 CONCLUSION 

The principal work of the division in the 
field of training was carried out by either the 
Selection and Training Committee or the train- 


276 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


in g groups associated with contractors’ labora- 
tories. The Training Committee and training 
groups performed complementary functions, 
and the majority of the situations encountered 
offered opportunities for both agencies to ren- 
der effective service. The committee was essen- 
tially a central advisory group of specialists, 
and the training groups were decentralized 
bodies of varying composition through which 
contractors’ facilities and personnel were ap- 
plied to the solution of specific training prob- 
lems. The centralized organization of the Train- 
ing Committee and its liaison with Navy of- 
fices and bureaus and with the other divisions 
and panels of NDRC were invaluable in pre- 
liminary surveys of fields of activity and in the 
initial formulation of problems and attacks 
upon them. On the other hand, members of the 
committee could not give their full time to the 
conduct or oversight of the programs widely 
distributed along both coasts and in forward 
areas. The training groups working immedi- 
ately out of the laboratories, or maintaining 
close connection with them, formed intimate 
local associations and conducted programs of 
selection and training in collaboration with 
schools and Navy commands. 

The training groups enjoyed a considerable 
freedom of initiative and liaison and the ex- 
perience that was gradually built up enabled 
them to render local assistance with the great- 
est benefit. Their decentralization was some- 
what of a handicap which was surmounted to 
some extent by intergroup reports and corre- 
spondence and frequent visits between the indi- 
viduals composing them. The absence of formal 
naval recognition through the issuance of orders 
to training assistants occasionally interfered 
with their effectiveness but was not always an 
unmitigated disadvantage. The partial and 
fragmentary information available to such 
civilian contractors’ employees likewise re- 
duced their general effectiveness, but this situ- 
ation was inherent in the principle of compart- 
mentation that was imposed. 

The most important observation that can be 
made on the operation of the training program 
is the crucial role played by the proper choice 
of participating personnel. The personal ability 
of a man in a key position may well make all 


the difference between the success or failure of 
the particular phase of the program with which 
he is charged. He must not only be technically 
competent, but obviously so, in order that he 
may gain the support of the naval officers with 
whom he is associated. He must have sufficient 
initiative and ingenuity to develop opportuni- 
ties for the exercise of the talents of himself 
and his associates, and the results that he 
achieves must be presented in sufficiently con- 
crete form for local Navy appraisal. The prac- 
tical approach and an understanding and rea- 
sonable frame of mind go far toward smoothing 
out the conflicting daily demands on personnel 
and facilities. Finally, it should be mentioned 
that discretion and local loyalty promote the 
assimilation of civilian assistance by naval ac- 
tivities and greatly facilitate cooperation. 

The successful operation of the training 
groups can be largely attributed to the support 
given them by the contractors’ laboratories 
which furnished shops, recording equipment, 
photographic and duplicating services, and 
staff specialists. The civilian organization 
would have been unable to function without in- 
dependent facilities and the ability to obtain 
rapid procurement of the various items needed 
in the course of its work. Reliance on Navy fa- 
cilities would have been quite impractical for 
many obvious reasons. The prestige associated 
with the laboratories was also in many in- 
stances of value to the training groups in the 
establishment of initial contacts. Another im- 
portant factor was the provision of travel and 
communication which are essential for ade- 
quate liaison between widely dispersed groups. 
One visit is worth innumerable letters and re- 
ports, particularly when the program is de- 
veloping rapidly and the status is represented 
by fragmentary data, personal opinions, and 
other tangible factors. 

A clear understanding of the complementary 
roles played by groups of civilian scientists and 
naval activities in a collaborative effort is par- 
ticularly conducive to the success of such an 
undertaking. The responsibility for the accept- 
ance and application of methods, techniques, or 
devices is that of the naval command. In this 
the scientist recommends, advises, and assists 
as the occasions warrant. On the other hand. 


CONCLUSION 


277 


the direction of the civilian scientific effort is 
not the province of the naval officer. If this re- 
sponsibility is assumed by him, there is then 
no need for duplicate scientific direction, and 
indeed it should be recognized that under such 
circumstances the caliber of civilian ability that 
should be associated with project direction can- 
not be retained. The general scope of a joint 
undertaking should be laid out by Service and 
civilian personnel in broad terms to achieve the 
ultimate objective agreed upon, and subsequent 
collaboration should be carried out in a spirit 
of mutual helpfulness but with the retention of 
independence of initiative and action on the 
part of both naval and civilian groups. 

On those occasions when this procedure was 
not followed, a marked reduction could be ob- 
served in the effectiveness of the combined 
efforts as judged by the results that were 
achieved on other occasions when the proper 
balance of responsibility was maintained. In 
some cases, joint efforts were initiated to ac- 
complish quite reasonable objectives, but the 
failure to appreciate the conditions necessary 
for success or the inability to bring these con- 
ditions about led to desultory progress or, on 
occasion, to abrupt cessation. In other cases, 
close and effective programs of collaboration 
were carried on between civilian scientific 
groups and naval commands which extended 
over the entire duration of World War II and 
increased in scope and value with successive 
changes of command and administration. 

Programs of civilian assistance are best ar- 
ranged on the basis of very considerable local 
autonomy. It is, of course, essential that deci- 
sions on objectives and general methods be 
made by central bureaus and integrating agen- 
cies, and such groups must be furnished with 
periodic reports in order that the benefits ac- 
cruing may be effectively and widely dissemi- 
nated. On the other hand, the local administra- 
tion in day-to-day contact with the work is in 
a better position to make appropriate decisions 
for the effective promotion of the program. 
Attempts to circumscribe local operations too 
closely, to specify details, and to designate the 
movements or activities of individuals invari- 
ably handicap and frequently seriously endan- 
ger the success of an undertaking. Here again, 


a nice balance must be maintained between 
civilian, advisory, and participatory functions, 
on the one hand, and central and local naval 
commands on the other. The establishment of a 
civilian technical group by higher authority 
initiates a permissive association which must 
be sympathetically accepted by the local com- 
mand if an effective contribution is to result. 
The situation is a voluntary one requiring good 
will and tact. Any recourse to authority would 
remove that freedom and flexibility which is 
necessary for the conduct of research and ex- 
periment and the immediate incorporation of 
its fruits in an urgent training program. 

The induction of civilians to this type of 
work requires a period of indoctrination in 
naval customs and procedures since ignorance 
of these matters may otherwise cause consider- 
able embarrassment. The assisting and advi- 
sory function of the civilians frequently re- 
quires emphasis on those occasions when in their 
excess of zeal they may tend to press for offi- 
cial action in too minatory a manner. An aware- 
ness of their own limitations of knowledge and 
experience must, however, be tempered by suf- 
ficient resilience and tenacity to surmount the 
first few negative reactions that frequently 
precede naval acceptance of novel procedures. 

The problems of the naval officer to whom 
civilian collaboration is offered merit some dif- 
fident comment as well. To the regular officer, 
such a proposal presents all the earmarks of 
irregularity and heterodoxy, and he tends to 
react with some skepticism. If, however, his 
first dubious and tentative essays at utilizing 
these services do not embarrass him but pro- 
mote the execution of his mission, requests for 
further assistance multiply with great rapidity. 
At this stage there is some likelihood that re- 
quests may be presented as orders, and willing- 
ness is expressed to take over completely the 
direction of the civilian group, employing it on 
routine matters. If this tendency is successfully 
and tactfully resisted and the direction of re- 
search and experimental programs retained in 
competent civilian hands, the way is open for a 
most fruitful collaboration. 

Precedent would be of great help in winning 
wars if each were fought like its predecessor, 
but, like all habit, it is an impediment to the 


278 


ASSISTANCE TO THE NAVY IN TECHNICAL TRAINING 


acceptance of new ideas. To the extent that it 
is a basis for many naval decisions, it must be 
recognized as repressive, but its baleful effects 
may be to some extent overcome by the mar- 
shalling of facts and the cogent presentation of 
an argument. The effort to secure the adoption 
of new training methods and techniques during 
a war may seem to impede the operation of 
combat operations. However, the advantages 
of making such changes in the full stride of 
a naval effort, when the hinging of success on 
adaptability renders the Service most receptive, 
far outweigh the disadvantages. The argument 
that it is possible to introduce new methods and 
procedures at any other time may well be ques- 
tionable. The Navy is well aware of the diffi- 
culties and delays in the long path of the de- 
velopment, testing, proving, manufacturing, in- 
stalling, and training for any new instrument 
or device. The slender peacetime budget with 
its close scrutiny by persons unfamiliar with 
the technical requirements of research further 
add to the Navy’s conservatism. 

This leads in conclusion to the question of 
the desirability of continued civilian participa- 
tion in naval training programs. This question 
might be considered in two aspects. The first is 
the benefit that might accrue to the Navy dur- 
ing peace, and the second is the advantage that 
might later appear on a declaration of war. 

The possible effectiveness of civilian partici- 
pation in either advisory or participatory ca- 
pacities during a period of peace would depend 
to a considerable extent on the naval policy 
pursued. Prior to World War II, naval training 
was a craft apprenticeship leading to a wide 
range of individual competence, but of a strictly 
standardized and rigidly specified type. The man 
of many enlistments was a jack-of-all-naval- 
trades at the particular level at which those 
trades were frozen at an earlier retrenchment. 
Naval techniques alter but slowly during peace- 
time, and a static system results which is highly 
resistant to change. The impact of war, how- 
ever, disrupts this system, bringing in new 
military methods and requiring the mass pro- 
duction and education methods which produce 
specialists in old as well as new techniques. 
These men have narrower ranges of individual 
competence, but are basically more flexible and 


receptive to changing circumstances and re- 
quirements. 

A service that might be performed by civilian 
participation in naval training programs in 
peacetime would be that of maintaining the 
germ or nucleus of the system of mass educa- 
tion of specialists that must be resorted to by 
the Navy at the onset of a major war. Periodic 
visits of interest and inspection to naval units 
and activities by civilian* training advisors 
would serve to give them some picture of the 
Navy’s day-to-day needs and problems. They 
would be but poorly qualified on such a basis to 
make recommendations in which they would 
have any great confidence, and in consequence, 
it is improbable that any important effect would 
be produced between wars by small-scale civilian 
participation in training matters. Also during 
such an interval, there is little motivation for 
the Navy or civilians, no compulsion to experi- 
ment with new methods, and, most important, 
no crucible of combat in which the success of 
new proposals can be unequivocally assessed. 

Considering the second point, namely, the 
value of a continuing program of peacetime 
civilian participation to the naval training at 
the onset of a war, certain definite advantages 
could be anticipated. The maintenance of a 
suitable civilian connection would serve to edu- 
cate specialists who were then to a considerable 
extent familiar with naval devices, procedures, 
and problems. They would understand the na- 
ture of the hibernant naval organization and 
could continuously study the methods and per- 
sonnel techniques by which it could be condi- 
tioned to the absorption of large numbers of 
additional personnel in war. These civilians 
could also establish contacts with naval officers 
and, in discussing such problems, get to know 
and be known by them to the extent that their 
role would be appreciated, and they would be 
able to contribute immediately and effectively 
should the cataclysmic occasion arise. One 
might conclude, however, with the cautionary 
remark that civilians are in no sense immune 
from the conservatism of age, and early retire- 
ments should be encouraged from such naval 
advisory groups to insure youthful and ener- 
getic consideration of the Navy’s problems and 
participation at need in its activities. 


Chapter 15 

FIELD ENGINEERING 

By Timothy E. Shea 


151 INTRODUCTION 

I N peacetime, the Armed Services and indus- 
try spend years in testing, proving and re- 
fining new devices or equipment, before releas- 
ing them for general use. They maintain huge 
proving grounds and employ elaborate systems 
for analyzing operational experience. Carefully 
controlled experiments, duplicating operational 
conditions, are performed under the direct ob- 
servation of engineers who are then able to 
make suggestions for changes or corrections in 
the design. 

In wartime, however, when there is a more 
urgent demand for new and improved devices, 
it becomes necessary for the engineer to leave 
his laboratory and go into the field. The battle- 
field becomes the proving ground. Since modern 
war has become to a large extent a war of 
gadgets, the advantage lies with the nation 
that can most quickly develop new or improved 
weapons and counterweapons. Because of 
war’s urgency, the periods of development and 
utilization must often overlap. 

Equipment for fighting men whose lives may 
depend upon its performance must meet a dual 
requirement. It must be dependable and rugged 
enough to operate beyond normal maintenance 
periods. In the case of the gear dealt with by 
Division 6, it might have to be designed to 
withstand the effects of pressure when sub- 
merged, or the corrosion of salt water, or the 
effects of tropical fungus growths, or the 
pounding of ship or airplane vibration, or the 
shock of depth-charge explosions. 

While meeting such stringent requirements, 
the equipment must at the same time be adapt- 
able to manufacturing techniques common to 
mass production; it must be capable of easy 
repair or replacement of parts ; and it must be 
accompanied by adequate technical informa- 
tion. It must be installed and maintained prop- 
erly. It must not be too difficult to operate and 
not be tricky in performance. It must be de- 
signed to be readily integrated with other ship- 
board or airplane equipment. 


The engineer and research worker have a 
personal as well as professional and patriotic 
interest in the proper design of war materiel, 
for, the shortcomings of a single piece of new 
equipment may not only cause a fighting man 
to lose confidence in its effectiveness, but also 
cause him to lose confidence in researchers and 
the whole research program. 

But the interest of the engineer does not end 
with design. In developing new equipment or 
devices, there is a complementary responsibility 
upon him to see that installation is correct, that 
technical information for operation and main- 
tenance is adequate, and that operation is not 
only satisfactory but carries out the basic ideas 
which lay behind the development originally. 
This is also true of techniques ; the applications 
must be appropriate. 

The Job of the Field Engineer 

The responsibility of getting new equipment 
into effective use is threefold. The operator asks 
that someone help him to obtain new tools. 
The developer designs the tools. Between the 
needs of the operator and the work of the de- 
veloper there is a gap which the field engineer 
must bridge. 

In bridging the gap, the field engineer must 
be concerned with problems of installation, op- 
eration, and maintenance. He becomes an ap- 
praiser and serves as liaison agent. He carries 
to the operator an appreciation of the prob- 
lems of the developer; he brings back to the 
laboratory the operator’s opinions on service 
requirements and operating conditions. The 
better these two groups mutually understand 
each other’s problems, the better it is for the 
whole process of development and application. 
The operations of the field engineer foster a 
close union of thinking between the developer 
and the operator. 

Therefore, in wartime, when equipment is 
proved on the battlefield, the field engineer be- 
comes responsible not only for installing a new 
device, testing it for malfunction and malad- 
justment, but he must also help train personnel 


279 


280 


FIELD ENGINEERING 


to operate and maintain new devices, so that 
they will gain the maximum benefit from their 
equipment. 

In the case of antisubmarine and prosubma- 
rine warfare, operations are conducted on the 
threshold of an instrument’s performance. 
Since first contact is extremely important, it is 
necessary to extract the last ounce of perform- 
ance from the equipment. Equipment must be 
in good condition and personnel must be able to 



Figure 1 . Field engineer inspecting projector 
in dry dock. 

operate it efficiently. Training and intelligent 
understanding of the use and limitations of 
equipment is important. This, of course, im- 
plies the coordination of men and equipment. 
All the men using the equipment must operate 
as a team. 

Men are usually trained to use equipment at 
the training centers. But the coordination and 
integration of the equipment is accomplished 
in actual service. There are many different 
kinds of equipment, made by different manu- 
facturers, at different periods. It becomes the 
duty of a properly trained field engineer to 
weld this equipment into a coordinated mech- 
anism, and, in some cases, it is his duty to weld 
both the equipment and men into an efficient 
team. 

In carrying out his manifold duties, the field 
engineer becomes a diagnostician and a doctor. 


Often he is a specialist, but to treat emergency 
cases he must also be a general practitioner 
with wide experience and knowledge of his sub- 
ject. 

Field engineers, recruited from American in- 
dustry and the university laboratories, played 
a vital role in the antisubmarine warfare of 
World War II. 


15 2 ORGANIZATION OF THE GROUP 

By 1942, the development and research 
projects of Division 6 were well under way 
throughout the United States. For instance, 
the Harvard Underwater Sound Laboratory 
[HUSL] in carrying out research on the 
improvement and modification of existing sonar 
gear, had installed auxiliary electronic devices 
aboard ship, and measured their performance. 
The furnishing of engineering service and op- 
erational training by HUSL was a logical and 
necessary part of the research program. 

During the latter half of 1942, and the first 
half of 1943, HUSL engineers made about 70 
installations of bearing deviation indicator 
[BDI] equipment, and in this process they dis- 
covered many cases of malfunction and malad- 
justment of equipment that had been previously 
installed. They made the necessary improve- 
ments and recommendations for corrections. 
Whenever possible, they acquired first-hand 
accounts of equipment performance from the 
operating personnel. This information was val- 
uable in making adjustments and adding im- 
provements to the gear in service, as well as 
revising BDI specifications. 

During 1942, experience with BDI installa- 
tions revealed that some of the streamlined 
domes installed around sonar projectors were 
interfering seriously with the establishment of 
normal beam patterns. HUSL had been study- 
ing beam-pattern characteristics and had de- 
veloped a useful device, the sound gear monitor 
[SGM] for determining the beam patterns. 
Therefore, the Atlantic Fleet administrative 
staff requested HUSL to carry out tests to 
measure the sonar directivity patterns for de- 
stroyers. 

Original instructions for sonar domes from 




ORGANIZATION OF THE GROUP 


281 


the Bureau of Ships (BuShips) had specified 
that they should be filled with antifreeze, anti- 
rust solution. Seventy vessels were tested and 
the investigation showed that the solution 
caused a waxlike deposit in the sonar domes 
which interfered with and tended to distort 
the beam pattern. HUSL engineers made recom- 
mendations for correction and later BuShips’ 
instructions were revised to provide for an- 
other kind of antifreeze, antirust solution. 
HUSL engineers were able to detect and cor- 



Figure 2. Checking a BDI installation. 


rect this trouble because of their wide knowl- 
edge of mechanics, chemistry, and acoustics. 
This is one example of how field engineers were 
able to “grease the wheels” of war operations 
by employing their diversified experience and 
knowledge. 

Need for Assistance 

By 1943, Division 6 of NDRC had become 
closely integrated with naval operations, design, 
and research, acting as a consulting body, in- 
venting and improving weapons and assisting 
in personnel training. 

Although a great deal was being accom- 
plished in developing new devices for detecting, 
locating, and destroying the enemy, it became 


apparent that more attention should be given 
to the problems of installation, operation, and 
training in the effective use of new antisubma- 
rine warfare weapons and devices. Also, ex- 
perience showed that the performance of older 
types of devices often could be substantially 
improved. 

Experience in peacetime had proved the need 
for coordinating the development, manufacture, 
installation, and operation of new devices. As 
the German U-boat threat increased, the need 
to bridge the gap between laboratory develop- 
ment and application of new devices grew more 
urgent. 

Several Division 6 laboratories had already 
found that they must render field engineering 
service if they were to do their job right. The 
research and development activities of these 
various groups created a problem in coordina- 
tion, evaluation, and use. 

Proposed Organization 

By early 1943, it had become clear that these 
various field engineering activities should be 
coordinated under one direction. Also, the Navy 
needed even more technical assistance in de- 
sign, installation, maintenance, operation, and 
training methods. 

Two ways in which the Navy and NDRC 
could meet the demand for this increased field 
engineering service were (1) the staffs of re- 
search laboratories could be expanded so that 
more men could be sent from the laboratories 
into the fields; (2) a special group of engineers, 
independent of the laboratories, could be re- 
cruited and trained in field engineering. 

If more men were sent out from the research 
laboratories, the research program undoubtedly 
would be hampered. Competent laboratory men 
might be wasted on field work for which they 
were inexperienced or unqualified. 

Specially trained field engineers seemed de- 
sirable. Preliminary discussions between the 
NDRC and the Navy were held and it was sub- 
sequently agreed that NDRC would set up a 
group of civilian engineers to render field engi- 
neering service to the Navy. 

Obviously, the functions of field engineering 
should be closely integrated with naval opera- 
tions and research. In forming the group, the 


282 


FIELD ENGINEERING 


Navy and NDRC were confronted with at least 
three plans of integration: (1) civilian engi- 
neers could be commissioned as Navy officers 
and serve as officer-engineers; (2) keep their 
civilian status and operate directly under 
NDRC; (3) keep their civilian status and oper- 
ate under Navy jurisdiction through existing 
organization lines. 

The first plan was discarded because it was 
agreed that engineers working as Navy officers 
would lose a certain freedom of movement essen- 
tial when speed and flexibility are at a pre- 
mium. The second plan was discarded as un- 
workable. The third plan appeared most satis- 
factory to both the Navy and NDRC. 

Just as it was necessary to integrate the 
NDRC laboratories under civilian direction 
with the organizational methods of the Navy, 
so it seemed necessary to integrate the field 
engineers with the Navy. 

Since field engineers deal with design infor- 
mation, and the bureaus are responsible for 
design in the Navy, it followed that the field 
engineers should operate through and for the 
bureaus on design matters. Also, since the naval 
operating forces are the sole customer-users of 
designed equipment, the thinking of field engi- 
neers must be identified with the objectives and 
situations of the operating forces. For these 
reasons it was decided that the group should be 
under the cognizance of the Bureau of Ships 
and that their orders and reports should be 
handled through Navy channels. 

This plan was agreed upon by the Navy 
and NDRC, and early in 1943 the Field Engi- 
neering Group was formally established under 
BuShips. 

The Navy Directive 

On April 27, 1943, Rear Admiral E. L. Coch- 
rane, Chief of the Bureau of Ships, issued a di- 
rective to all ships and stations announcing the 
formation of the Field Engineering Group by 
the Bureau of Ships, with the assistance of the 
NDRC, and with the cooperation of the Bureau 
of Ordnance, the Vice Chief of Naval Opera- 
tions, and the Commander-in-Chief. 

The directive was issued on May 1, 1943, as 
Navy Bulletin C-157 and defined the purpose, 
scope, and mode of operation of the new group. 


The purpose, as stated by Admiral Cochrane, 
was: 

(1) to directly serve the naval shore establishments 
and through them the fleets and forces in this interest 
(of improving the technique of installation, maintenance 
and operation of antisubmarine equipment) ; (2) to 
gather and publish information for service use on 
antisubmarine equipment; (3) to permit the National 
Defense Research Committee to obtain first hand con- 
tact with the problems of antisubmarine warfare in 
order to increase its usefulness to the Navy. 

[Personnel for field engineering service was to be] 
selected from experienced civilian engineers, well- 
qualified by training and temperament to make them- 
selves effective in work with other personnel, [to be] 
obtained from the ranks of NDRC and loaned to the 
Navy for this extremely important work. 

[Field engineers while on duty were to be] directly 
under naval jurisdiction and . . . make their reports to 
the Chief of the Bureau of Ships, via the naval officer 
to whom they report. The personnel involved [were to 
be] governed by such directives as ... in effect or 
published from time to time with Naval approval. 

To permit effective liaison in all antisubma- 
rine warfare matters, the bureau assured the 
availability of representation from the engi- 
neering service to other interested bureaus, the 
chief of Naval Operations, and the headquar- 
ters of the Commander-in-Chief. 

[It would be the Bureau of Ships’ responsibility] to 
disseminate the information and data collected from 
the field to the interested bureaus, offices, commands, 
manufacturing establishments, and research and de- 
velopment institutions. 

[The bulletin then stated] it is expected that the 
Bureau of Ships will use the talents of field engineers 
to the fullest extent in composing reports and direc- 
tives concerning the subject. 

Field engineers were to report to the chief of 
the Bureau of Ships, for assignment to field 
engineering duty “in matters on installation, 
maintenance and operation” at the following 
activities within established naval districts : 
Navy yards; industrial managers; naval sta- 
tions; naval operating bases; naval schools; 
inspectors of naval materiel; laboratories con- 
ducting antisubmarine warfare investigations; 
interested bureaus or offices of the Navy De- 
partment. 

When the field engineers were assigned to an 
activity within a naval district they would op- 


ORGANIZATION OF THE GROUP 


283 


erate under existing organizational lines. The 
bulletin stated : 

In the case of an engineer, for example, assigned to 
a Navy yard, the commandant will direct him to report 
to the radio material officer during such time as he may 
be engaged in work involving projects in radio, radar 
and underwater sound material. Simultaneously he may 
be directed to report to the ordnance officer for work in 
connection with depth charges or other ordnance 
weapons. [And finally,] in order that effective help in 
problems of antisubmarine warfare may be obtained 
from field engineers by the Navy, all commanding 
officers are enjoined to make full use of this service at 
each opportunity presented and to offer these engineers 
every possible assistance. 

The directive referred only to antisubmarine 
warfare, but the scope of the Field Engineering 
Group later included assistance and training 
not specifically mentioned by Admiral Coch- 
rane. 


Formation of the Group 

On the basis of the Navy directive, the Field 
Engineering Group was organized and admin- 
istered by Columbia University Division of 
War Research [CUDWR], under an OSRD 
contract. T. E. Shea had general charge of the 
group, which was directed first by J. W. Ken- 
nard and later by Woodman Perine. 

In assigning the task to CUDWR, Dr. John 
T. Tate, chief of Division 6, wrote Shea a letter 
of guidance specifying certain basic principles 
which should govern the activities of the group. 
Excerpts from the letter follow : 

I have noted the issuance by Admiral Cochrane of 
the Bulletin announcing to all ships and stations the 
establishment and mode of operation of the Field 
Engineering Group which Division 6 of the National 
Defense Research Committee is making available to 
the Navy. 

I am asking that you assume, under Dr. E. H. Col- 
pitts, Chief of Section 6.1 of Division 6, responsibility 
for the conduct of this enterprise insofar as the re- 
sponsibility of the National Defense Research Com- 
mittee extends. It is my understanding that this re- 
sponsibility will include the selection, training, and 
indoctrination of the members of the group, the estab- 
lishment of its internal organization, and, subject to 
the policies laid down in Admiral Cochrane’s bulletin, 
the delineation of the responsibilities and methods of 
operation of the group. 


Since the task of the Field Engineering Group for 
which you are responsible will, of necessity, impinge 
upon matters which lie in several different areas of 
functional responsibility in the Navy and in the Na- 
tional Defense Research Committee, it will be essential 
that you rigidly adhere to and respect the lines of re- 
sponsibility and duties of the several branches of the 
Navy and of NDRC. The success with which this can 
be done will, to a large extent, determine the usefulness 
of the Field Engineering Group. 

For your guidance, I am setting down my under- 
standing of the basic principles of operation of this 
group : 

1. The group as a whole is to interest itself broadly 
in anti-submarine detection equipment, specialized anti- 
submarine ordnance, related conning aids, and other 
associated devices used in detecting and attacking sub- 
marines. This includes equipment of existing types as 
well as newly developed equipments or equipments to 
be developed in the future. 

2. The group will render assistance to the Bureau of 
Ships, Bureau of Ordnance, Commander-in-Chief 
[Readiness], and other Navy groups in the rectification 
of specific installation, maintenance or operating 
troubles. 

3. The group is to keep in mind that installation, 
maintenance, and operations are to be improved not 
alone by the correction of spot situations, but even 
more importantly by discovering through analysis of 
experience troubles of a recurrent or persistent nature 
and the institution of corrective actions of a general 
nature. This latter work is, of course, merely the con- 
cluding part of any practical development engineering 
work, insuring that equipment is suitable to the use 
intended. Where justified, recommendations for such 
corrective actions are to be made by the group through 
the Bureau of Ships to the appropriate Bureaus or 
Offices or to the appropriate National Defense Re- 
search Committee groups. 

4. The group will note that a close inter-relation 
exists between the performance of equipment and the 
type and training of the personnel which maintain and 
operate it. The group will interest itself, therefore, in 
operations with the special aim of obtaining insight into 
ways of improving adaptation of equipment to the 
existing background and experience of its users. 

5. Individual members of the group will realize that 
their effectiveness depends to a large degree on the 
manner with which they handle themselves in their 
everyday relationships with Naval personnel in informal 
dealings, and will accordingly endeavor to conduct them- 
selves with the maximum of tact and discretion con- 
sistent with getting their jobs done. 

6. For the purpose of providing members of the 
group with Naval sanctions and entrees, the field 
assignments of members of the group will be under 
authorizations and instructions from the Chief of the 
Bureau of Ships. The Navy directive covering this 
group states that ‘Field engineers, while on duty, will 
be directly under Naval jurisdiction.’ I understand 


284 


FIELD ENGINEERING 


this to mean that they must conform to all rules and 
regulations of the station to which they are assigned 
and generally conduct themselves as on loan to, and 
for the time being an integral part of, the Navy organ- 
ization. 

7. It is important that the collection and distribution 
of information derived from the endeavors of this group 
be coordinated with the effort of the various Naval 
branches. You are therefore to see to it that such in- 
formation is centrally collected and its distribution is 
centrally supervised in such a manner that the re- 
sponsibilities of the various Naval agencies are properly 
served. It is for this reason that the Navy directive 
covering this group refers to reports being rendered to 
the Chief of the Bureau of Ships. It is expected that all 
such reports will flow in the Bureau of Ships to the one 
whom you may designate in the Field Engineering 
Group, so that he may digest them and recommend 
appropriate action and so that there may exist in one 
place as comprehensive a view of the field situations 
and their related problems as possible. It will, in this 
connection, be the particular responsibility of the head 
of this group so to arrange matters with the Bureau of 
Ships that an adequate flow of development criticisms 
and suggestions accrues to the National Defense Re- 
search Committee groups on matters of concern to 
them. 

8. In this latter connection, you will especially bear 
in mind that the National Defense Research Committee 
laboratories will be looking to your group, subject to 
proper channelizing through the Bureau of Ships, for 
the obtaining of valuable constructive development 
criticisms and suggestions. 

9. A general liaison will be maintained with the 
Bureau of Ships and the Field Engineering Group by 
this office to the end of insuring that the National De- 
fense Research Committee is providing for this work 
facilities and assistance of the types needed for it, and 
that the scope of the activities of the group are such 
that the National Defense Research Committee’s par- 
ticipation in it is a logical and natural one. 

Steps were promptly taken to organize the 
group on the basis of Admiral Cochrane’s direc- 
tive and the division chief’s letter of guidance. 
The headquarters office was established in the 
Underwater Sound Installation and Mainte- 
nance Section of the Radio Division, Code 983, 
in the Bureau of Ships. The director and his 
assistants were located there. Business man- 
agement, personnel and procurement of equip- 
ment and supplies were handled by a small staff 
at 172 Fulton Street, New York City. Field 
headquarters, including the training and infor- 
mation bureau, were established at the. New 
London laboratory of Columbia University. 

The next step was to recruit civilian engi- 


neers for training. Since only a few men at the 
New London laboratory and other Division 6 
main laboratories could be spared for work on 
the new project, it was necessary to look else- 
where for personnel with the required experi- 
ence and personal qualifications. 

Recruiting of Personnel 

The chiefs of both the Bureau of Ships and 
Division 6 recognized certain factors involved 
in the integration of the functions of field engi- 
neering with the Navy. Some of these were: 

1. The Navy is necessarily a complex organ- 
ization, based principally on considerations 
other than those involved in performing tech- 
nical work in a specialized field. 

2. The Navy had expanded rapidly in both 
materiel and personnel. 

3. Operations are paramount, and materiel 
and training are but a means to an end. 

4. A process of orientation and adjustment 
of civilian engineers to Navy conditions and 
practices is necessary and this takes some time 
to accomplish. 

5. It also takes time for naval officers to 
understand how best to use civilian assistance. 

6. The application of electronics to naval 
operations had increased greatly and learning 
the techniques, equipment, and methods of use 
had created a huge problem. 

7. The tremendous dimensions of the war, 
geographically and in relation to national pro- 
duction capacity, had disarranged the orderly 
procurement and distribution of materiel and 
personnel. 

There were other factors which have a bear- 
ing on the problem of effective utilization of 
civilian engineers. Because of these factors, and 
because of the nature of field engineering, cer- 
tain characteristics which field engineers should 
have were determined. 

These included: (1) good technical ability, 
(2) emotional stability and adaptability to a 
variety of work and conditions, (3) ability to 
criticize equipment constructively for opera- 
tions, (4) practical ability to use tools and a 
“nose for trouble,” (5) eagerness and aptitude 
for passing on to others the knowledge and ex- 
perience acquired, (6) ability to work through 
organization channels, (7) ability to command 


ORGANIZATION OF THE GROUP 


285 


the confidence and respect of commanding offi- 
cers, (8) resourcefulness and an ability to 
handle emergencies, (9) a strong sense of re- 
sponsibility to people, a “feeling for service.” 

The age of 35 to 40 years was considered 
ideal since men of that age would be old enough 
to have the necessary experience and young 
enough to stand the pressure. 

After a survey of the scientific and industrial 
fields, it appeared at first that the communica- 
tions and power industries had a reserve of 
electronic and mechanical engineers whose in- 
dustrial experience gave them the necessary 
know-how for the job. It was soon discovered, 
however, that the communications field had al- 
ready been drawn upon heavily, so a substantial 
number of engineers were recruited from power 
companies and other sources. 

The group was formed around eight men 
from the New London laboratory of Columbia 
University, who had already been doing some 
field engineering. These men were immediately 
given special training for their new job and the 
Personnel Branch started recruiting additional 
engineers. 

Industrial and other organizations were 
urged to lend some of their best men to the 
group, and the companies released the men 
wanted on leaves-of-absence. 

Wartime recruiting was difficult not only be- 
cause of the heavy demand for qualified engi- 
neers by the Armed Forces and manufacturers, 
but also because the necessity for security made 
it impossible to explain the requirements in full 
detail. 

These requirements, determined when the 
group was formed, were based on an analysis 
and estimate of the nature and extent of the 
job to be done and they were altered very little 
during the life of the group. 

Men with field and appraisal experience were 
preferred to men with only developmental ex- 
perience. Special efforts were always made to 
secure qualified men who were tactful and ex- 
perienced in handling people. 

Eighty-one engineers were recruited from 
telephone companies, radio broadcasting sys- 
tems, power companies, schools and colleges, 
manufacturing companies, and government 
agencies. Their experience in these fields 


ranged from 4 to 24 years, averaging 15 years. 
Thus men of similar caliber but with widely 
varied specific experience and background were 
secured. 

Training and Indoctrination 

As the men were recruited and accepted, they 
were sent to the New London laboratory for 
training and indoctrination. The field engi- 
neer’s training included: (1) a comprehensive 
introduction to the fields of underwater sound 
and antisubmarine warfare, (2) indoctrination 
in Navy customs and traditions, and (3) train- 
ing in the Navy’s organizational structure and 
operating methods. 

Later, training courses were broadened to 
cover airborne ASW equipment and the pro- 
submarine warfare equipment developed for 
the Pacific Fleets. In conducting these courses, 
lectures were given by laboratory staff mem- 
bers, naval officers representing the Bureaus 
and Fleets, personnel from other research lab- 
oratories, representatives of manufacturers, 
and later, by experienced field engineers. 

The naval training centers made available 
ASW practice equipment for the trainees. The 
group went on many trial operations conducted 
at sea and made visits to factories, naval bases 
and stations, and research laboratories. Some 
field engineers were employed for months on 
laboratory developments so that they could 
learn all the details of certain newly developed 
pieces of equipment. Engineers usually spent 
a brief period in the Bureau of Ships to learn 
bureau procedures and to meet the personnel. 
The period of training varied from several 
months to more than a year, depending on the 
need for the engineer’s services and his indi- 
vidual capabilities. 

To show how this work differed from that of 
a laboratory or manufacturer’s group, here are 
excerpts from an initial lecture by T. E. Shea 
in the engineers’ training course: 

In its work, the Field Engineering Group must 
especially adopt a detached and unbiased point of view 
with regard to devices and their use. The natural 
enthusiasm of development people for devices on which 
they have worked, which enthusiasm is one of the driv- 
ing forces of development people, has as such no place 
in the thinking of the group. It is as tools for the 


286 


FIELD ENGINEERING 


Navy to use that the group must have enthusiasm for 
these — and as practical tools actually becoming avail- 
able. 

On the other hand, the group must realize that new 
devices can be appraised only when conditions for 
appraisal are right, and as shortcomings in design and 
performance are removed or improvements incorpo- 
rated. The group can therefore stimulate and make 
more productive the work of laboratories by applying 
to their product the acid test of just, practical, and 
imaginative analysis. . . . 

This group cannot do more than a fraction of the 
work that is to be done. Its objects must therefore be 
(1) to look back on having done a lot of good for a 
lot of vessels, and as the latter can be reached; (2) a 
shortening of the time required for given vessels to 
achieve efficient operating situations. . . . 

In their capacity as field engineers, members of the 
group will . . . interest themselves broadly in all phases 
of anti-submarine warfare equipment, and are to seek 
out opportunities to help Naval personnel, formally 
or informally. Often this may result in unexpected 
ways by the simple process of familiarizing themselves 
with the existing equipment and personnel situations, 
and discovering whether it is satisfactory. They are 
looking for trouble only if it exists but will find out 
whether it exists by getting around and getting 
acquainted. 

They should be cautious: (1) not to excite desire 
for as yet undeveloped equipment which the ships 
cannot have for some time; (2) not to excite pessimism 
regarding equipment which may not be all that it 
ideally should be; (3) not to preach doctrines in respect 
to use of equipments which are unsanctioned. 

In other words, the aim is to do the best we can 
with the equipment and personnel we have, until and 
unless we can get replacements. They should constantly 
be on the lookout, and report on, situations seeming to 
require action as a class. . . . 

The field engineers should secure the acquaintance 
of such manufacturer’s representatives, and exchange 
mutual help. They can help us by information on their 
equipment. We may be able to assist them with BuShips 
or otherwise on problems. The better they can do their 
jobs the less there is for us to do — and this should be 
our aim. 

The Manual 

An important part of training field engineers 
was the unique volume, The Field Engineering 
Manual. For convenience, a wide variety of in- 
formation on installation, maintenance, and op- 
erations was collected in a single volume in 
order to digest essential information from Navy 
publications, to permit continued study by en- 
gineers, to enable them to keep up to date on 
new equipment as it was released, to provide 
information in compact form not otherwise 


available, and to provide material suitable for 
informal or formal training of naval personnel. 

Very little material produced by others was 
used as originally published and much infor- 
mation was developed on new devices from the 
ground up, and was issued ahead of the manu- 
facturers’ regular instruction books. An exam- 
ple of this is the attack plotter guide, discussed 
in another section. 

Field Training 

The first group of field engineers to go out 
under Navy orders to various Navy yards did 
not have the benefit of advanced field training. 
Subsequent groups were first assigned to work 
with and assist senior field engineers who had 
already been on the job. It was of considerable 
value to all of the men to have this active and 
informal help in getting acquainted with actual 
operations in Navy yards and stations before 
undertaking the responsibility alone at a new 
activity. 

Refresher and Special Training 

To insure the continuing usefulness of the 
group to naval operating forces, men were 
brought back from time to time to laboratories 
and factories to receive refresher training on 
equipment in the final stages of development 
or in production. In each case they returned to 
the field bringing up-to-date and current infor- 
mation on new equipment about to arrive in the 
Navy. This refresher training program, in re- 
verse, made it possible for the engineers to 
convey the field point of view to the laboratories 
and factories. 

15 3 OPERATIONS OF FIELD ENGINEERS 
Scope of Activities 

When the group was formed in 1943, men 
were assigned, as directed by Admiral Coch- 
rane, to the various Navy yards in the conti- 
nental United States, under cognizance of the 
radio material officer (RMO) and in several 
cases under the ordnance officer, to fill the most 
pressing needs at that time. 

Engineers were assigned to give technical 
assistance to RMO’s making installations of 




OPERATIONS OF FIELD ENGINEERS 


sonar equipment. Having an experienced engi- 
neer from industry who had the installation, 
maintenance, and field point-of-view was an 
advantage, since most civilian employees in the 
yards were not familiar with the practical ship- 
board use of echo-ranging and sound equip- 
ment. 

During this period, the field engineers made 
in-the-water checks of sound gear and cleared 
up difficulties arising from the adaptation of 
new devices to existing equipment. This sur- 
face ship activity naturally evolved into certain 
assistance to operating bases in the continental 
United States. 

At the operating bases, field engineers were 
asked to assist in tactical operations, in train- 
ing, and in the evaluation of equipment, and in- 
formally made modifications in operating tech- 
niques. 

Having had some experience in Navy yards 
and operating bases, it was natural that engi- 
neers should begin to collaborate with labora- 
tories and manufacturers, exchanging informa- 
tion on sonar and ordnance development. The 
engineers were building up an experience which 
could be used to mutual advantage in planning 
equipment and suggesting programs for schools 
and training activities. Because of the interest 
of the bureau and through the engineers’ per- 
sonal contacts, training activities and training 
centers accepted their assistance. The engineers 
could give a kind of help not readily obtainable 
from either officer or enlisted personnel. 

During and following the transition from 
antisubmarine warfare to prosubmarine war- 
fare, the men assisted in prosubmarine warfare 
much as they assisted in antisubmarine war- 
fare. 

It may be that it would have been well to 
have set up the forward area coverage sooner, 
but perhaps this final phase of field work could 
only have been done after gaining previous 
experience elsewhere. 

As time passed, opportunities developed to 
serve outside the narrowly defined limits of 
the original directive and this led to such ac- 
tivities as distributing technical bulletins to 
Navy personnel, establishing formal training 
schools, and developing certain testing tech- 
niques which were adopted as standard proce- 


287 


dure. Examples of these types of additional 
services are discussed in Section 15.4. 

As the organization grew in numbers and 
experience, additional assignments were made, 
until in the final year of operation, there was 
a heavy concentration of men with the forces 
afloat. 

Field engineers served at 68 establishments 
and headquarters in 14 naval districts ; in 8 sea 
frontiers ; with 4 Fleets and groups in the 
Atlantic; 8 Fleets in the Pacific; at 16 schools 
and training activities ; and at 6 laboratories. 

They served at Navy yards, operating bases, 
Navy commands and with the forces afloat from 
North Africa and Europe, through the Carib- 
bean, across the United States, through the 
Pacific islands to Australia. 

During a typical week, 60 engineers would 
be on field assignment and at least 50 of them 
would move during the week. At any time of 
the day or night, an engineer might receive 
orders to pack his gear, catch a plane and re- 
port within 24 hours to a base 3,000 miles away. 
Within the United States they traveled by 
means of public carriers, but most of their over- 
seas transportation was provided by the Navy. 

The men usually traveled alone or in pairs, 
but on one occasion it was necessary to send 
15 men on one ship to Pearl Harbor. 

Their casualty and sickness record was ex- 
cellent. No engineer was killed on duty and only 
a few were injured in accidents. This does not 
mean they were not exposed to risks. More than 
one engineer escaped death by having been 
“bumped” from a plane that later crashed. 

The need for strict security measures to pro- 
tect vital information is obvious. But so far as 
is known no attempts were ever made to steal 
data and all material issued to the men in the 
field was returned or accounted for when the 
group was terminated. 

Information Branch 

From the first, it was recognized that an 
information service must be maintained to keep 
the engineers fully informed on developments 
affecting their work, thus assuring their value 
as consultants to the Navy. 

Technical information was compiled from 






288 


FIELD ENGINEERING 



Figure 3A, B. Views of sonar maintenance school under cognizance of ComServPac. 




OPERATIONS OF FIELD ENGINEERS 


289 


every available source. A complete library and 
file of instruction books were established, and 
the field manual was begun. The information 
branch was organized to provide this service 
and to act as a clearing house and source for 
assisting the engineers in the field. 

Information flowed to the engineers from 
three principal channels : (1) the manual; (2) 
In-Between and special bulletins; (3) corre- 
spondence and wire communications. 

The manual has been described in another 
section. In-Between was a monthly house organ 
which contained items of general interest, tech- 
nical items, news about the work and life of 
the men at all stations, and administrative 
news. 

Innumerable requests for information on 
specific equipment or special problems con- 
fronting individual engineers were received at 
the New London information branch. Each 
request was answered as promptly, completely, 
and accurately as possible. In many cases, mem- 
bers of the information office would have to get 
the answers from other laboratories or manu- 
facturers. 

An example will illustrate how this service 
operated. The field engineer assigned to the 
submarine base at Perth, Australia, discovered 
that submarines on war patrols and other oper- 
ations in the Philippines area, were operating 
with high sound levels, making them subject to 
easy detection by the Japanese. At first, the 
field engineer not only had trouble in locating 
the source of the high sound levels, but he also 
had trouble in persuading the submarine offi- 
cers to improve their boat conditions, such as 
rattling deck slabs, vibrating plates on super- 
structures, squeaky shafts, and noise due to 
wear and tear. The field engineer decided that 
he needed a sound recorder to record the boats’ 
sound and then play it for the skippers and 
electronics officers. 

He cabled the New London information engi- 
neer to rush a recorder to Perth. To speed 
delivery, the information engineer cabled the 
field engineer at Pearl Harbor and asked him 
to ship his recorder to Perth and at the same 
time told him that a new one was being shipped 
from the mainland to replace the one to be 
shipped to Perth. The sound recorder did the 


job expected of it. The submarines operating 
out of Perth were made significantly more 
silent. 

For another example, the radio material offi- 
cer at Pearl Harbor had a tremendous job of 
keeping the sonar equipment of hundreds of 
ships in operation. One of his continuing prob- 
lems was to determine if one piece of equipment 
could be substituted for another. For instance, 
were the electronic characteristics of two pieces 
of equipment the same? Also, at advance bases 
a table of sonar projector characteristics was 
urgently needed that would show the inter- 
changeability of parts. The RMO knew about 
the Field Engineering group, and asked the 
engineer attached to CINCPAC to provide the 
information. The engineer cabled New London, 
and within a few days the projector character- 
istics table was produced and several hundred 
copies were printed and flown to Pearl Harbor 
for distribution to all essential Pacific locations. 


Operations Statistics 

Because of the far-flung and diversified na- 
ture of the Field Engineering group’s work, 
the heavy demand for its services, and the per- 
sonnel shortage, it was never possible to make 
statistical studies of the work performed. 

For example, there are no figures to indicate 
how field engineering improved the efficiency 
of submarine or ship sinkings, since it was 
never possible to isolate all the factors involved 
in an ASW operation. Neither was it possible 
to determine how much field engineering in- 
creased ASW crafts’ operating efficiency. When 
a ship arrived at a yard for repairs, a certain 
number of days were allotted for making all 
repairs, and at the end of that time the ship 
returned to sea duty whether ready or not. 
During this time the field engineer might be 
called upon to check and repair the entire sonar 
system, and he had to complete the job in the 
allotted time. So, field engineering did not nec- 
essarily help speed the return of craft to war 
patrol. But field engineering did increase the 
efficiency and coordination of the men and 
weapons. 

A specific example will indicate the impossi- 


290 


FIELD ENGINEERING 


bility of measuring the work of any one field 
engineer. A certain engineer, who had just 
completed his training, was sent aboard a ship 
at Boston to assist in installing a stop-gap 
model of an attack plotter. When the job was 
completed, he was invited to go on the shake- 
down cruise. During the cruise, he checked, 
tested, adjusted, and repaired not only the 
sound equipment, but practically all other ship- 
board equipment. He was virtually shanghaied 
by the ship’s crew for several weeks. Finally, 
he left the ship at a Navy base at Bermuda, 
but here he found waiting for him more jobs 
than he could handle. Each day for several 
weeks he went out on vessels in ASW practice 
operations, working as a free-lance mechanic 
and troubleshooter, wherever he was needed. 
Obviously, it was impossible to measure the 
results of the thousands of jobs done by this 
man. 

Many of the jobs done by field engineers were 
determined by whether the man had the flexi- 
bility and versatility (which depended on his 
particular training and background) to handle 
on-the-spot jobs that suddenly developed. In 
many cases an engineer would be assigned by 
a commandant to fix a specific situation and in 
doing so he would discover several other diffi- 
culties which needed clearing up. 

Thus to classify and measure the work of 
any one man, or the group as a whole, would be 
extremely difficult without a large statistical 
staff, which the group never had. An under- 
standing of what field engineering accomplished 
may, however, be gained through consideration 
of some examples of the kinds of work the 
group did. 

The examples are grouped under four classi- 
fications. The material has been abstracted 
from more than 400 engineering reports made 
through Navy channels, as well as from corre- 
spondence and informal reports. 

15 4 THE FUNCTIONS OF FIELD 
ENGINEERS 

Although the problems of field engineering 
were complex and varied, it was possible to 
divide the functions of the group into four cate- 
gories: (1) giving staff assistance, (2) detec- 


tion of fundamental equipment difficulties, (3) 
introduction of new equipment, and (4) devel- 
opment of new systems and techniques of using 
equipment. 

The story of the development, production and 
installation of the attack 'plotter [AP] is a good 
illustration of the varied and specialized func- 
tions of field engineering. 

An attack plotter, as has been already noted, 
is a visual conning aid used in antisubmarine 
attacks and is now standard equipment on de- 
stroyer escorts and other ASW craft. This 
device, based on a course-plotting application 
of the cathode-ray tube, was developed by the 
General Electric Company under an NDRC 
contract. The New London Laboratory in 1942 
had appraised it in comparison with two other 
plotting systems, and recommended its produc- 
tion. At about the time the Field Engineering 
group was organized, Bureau of Ordnance con- 
tracts for manufacture were let. 

Here was a new and complicated electronic 
device. There would be design and production 
problems, problems of distribution, installation, 
and problems of integrating it with all other 
shipboard equipment. Men would have to be 
trained to use it. 

To operate successfully, the AP had to be 
coordinated with three other information sys- 
tems aboard ship. In most cases these systems 
were manufactured by different companies, in- 
stalled and maintained by different personnel. 
Therefore, introducing the AP would require 
engineers familiar with all antisubmarine 
equipment. 

The field engineers were able to foresee the 
problems and take action in advance to solve 
them. And when the units came off the produc- 
tion line, the engineers' were ready to help put 
them to work. 

As a part of their training, the engineers 
were sent to General Electric plants. They 
studied the theory and design of AP’s, and as- 
sisted in designing and testing circuits and cer- 
tain components. They worked with the com- 
pany engineers, studying part replacements and 
adjustments. They even helped to draw circuit 
diagrams. When the AP was ready for sea 
trials, the field engineers made the arrange- 
ments and supervised the tests. Engineers as- 


THE FUNCTIONS OF FIELD ENGINEERS 


291 


signed to the factory sent technical information 
to the engineers in the field who were working 
on introductory plotter problems. 

Meanwhile the company was preparing an in- 
struction book on the Bridgeport model. But 
production of plotters ran ahead of the manu- 
facturer’s editorial work and AP’s were reach- 
ing the Fleets without instruction books. At the 
same time the Information Branch of the Field 
Engineering group was preparing a manual for 
its field men. Because of certain differences in 
the stop-gap and production models being man- 
ufactured at Pittsfield and Bridgeport, different 
engineering information had to be provided for 



Figure 4. Checking attack plotter chassis under 
the guidance of a field engineer. 

the two different models. Instruction manuals 
were urgently needed by the Navy personnel 
and field engineers who were receiving the new 
equipment. 

The field engineers had followed the develop- 
ment and production of AP, and were assigned 
to compile technical information for the GE 
manual. Since it could not be issued in time to 
meet the demand, they issued interim instruc- 
tion bulletins. This interim instruction material 
was shipped with the first 100 plotters, and 
additional copies were distributed by the Navy 
and group both to naval personnel and field 
engineers. 


Even after the company’s manual was pub- 
lished, many ships continued to use the pre- 
liminary instruction material as an operating 
guide, because of its convenient form. 

Among the first groups of trainees, several 
men who specialized in the theory and design 
of the AP, and company engineers, who had 
developed the device, formed the nucleus of a 
teaching staff for new engineering trainees and 
Navy personnel. 

By the end of 1943, AP’s were flowing to the 
Fleets in great numbers and every field engi- 
neer had had some experience with installation. 

Field engineers on duty in the plants alerted 
the men in the field on the date of arrival of the 
new plotters. Engineers in the field at first 
encountered difficulties, mostly of a minor na- 
ture, in installing and using the new devices. 
But the plotter experts still at the GE plant 
were able to send information to help clear up 
these difficulties. 

With any device of this kind, which takes 
information from a variety of sources aboard 
ship, difficulties are encountered which increase 
with the number of systems involved. Although 
the plotter had been well designed and well 
built, certain operational difficulties were en- 
countered at first and field modifications had 
to be made. Because field engineers had been 
specially trained, they were able to make these 
modifications promptly and suggest corrections 
or changes to the Bureau of Ships which for- 
warded them to the manufacturer. 

But AP units were reaching the Fleets faster 
than the engineers could handle them. Between 
October 1943 and April 1944 about 500 AP’s 
were shipped out, and only 53 field engineers 
were available to introduce the equipment as it 
arrived. These men also had many other duties 
and could not devote all their time to the new 
device. Also, very few manufacturer’s field rep- 
resentatives were available to assist in install- 
ing the equipment and instructing personnel 
how to use it. 

To speed up the installations, plotter experts 
were sent out as flying squadrons to all loca- 
tions installing the AP. One such squadron of 
two men traveled 15,000 miles in less than a 
month, visited 26 Navy and civilian yards and 
ASW training centers and gave instruction to 


292 


FIELD ENGINEERING 


more than 200 installation and maintenance 
men. 

Practically every member of the Field Engi- 
neering group worked on the AP problem, and 
it is safe to say that the field engineers or 
personnel whom they had trained supervised 
the installation of every AP in the Fleets. 

In handling this one problem, the group per- 
formed all of its four major functions. It gave 
assistance to naval commands and training 
staffs. It detected and corrected fundamental 
difficulties in the first AP’s. It introduced the 
equipment to the men of the Fleets and in doing 
so, developed new systems and techniques for 
antisubmarine warfare. 

Other examples of the work of the Field En- 
gineering group may be mentioned. 


15,41 Staff Assistance 

Field engineers offered technical advice to 
the various staffs and served as general con- 
sultants, appraisers of equipment, organizers 
of installation and maintenance procedures, and 
advised on training instructor personnel. 

The engineers’ contact with the Fleets had 
revealed to them a serious and urgent need for 
better trained and better informed personnel. 
Naval operations were badly hampered during 
the first part of World War II by lack of train- 
ing facilities, inadequate technical information 
and inadequately trained instructor personnel. 
Here was another problem for the Field Engi- 
neering group. 

As soon as the group was organized, it went 
to work to establish better naval training facil- 
ities. It had ships assigned to training activities 
and sent urgent reports to BuShips on the need 
of more and better training facilities. 

Before the engineers could become instruc- 
tors, they often had to become familiar with a 
whole new field of knowledge in a few days. 
For instance, one group of engineers took a 
two-hour course on how to man sound gear and 
fire control, and how to helm and conn the ship. 
The men who had been recruited proved adapt- 
able in learning tactical as well as operational 
and electronic problems. They could discuss 


tactical and operational problems with the skip- 
per, answer questions on operation of gear, and 
instruct the crew on adjusting sound range 
recorders and improving the accuracy of tar- 
get-hitting and depth-charge dropping. 

In 1944, ComServPac requested the group to 
help prepare a curriculum for sonar mainte- 
nance at the Pearl Harbor Radar School. This 
school was to train qualified radar technicians 
to maintain shipboard sonar equipment. Some 
students came from the Radar School, and 
others were taken from ships, were trained, 
then returned to duty. 

The school opened on November 1, 1944, and 
field engineers served temporarily as instruc- 
tors until new instructors were available from 
the ASW Training Center. 

Since the students who came from the ships 
knew what type of gear they would have to 
work with when they returned, it was possible 
to concentrate on information of immediate use 
to them. The school concentrated on gear widely 
used by the Navy rather than on new equip- 
ment — at least until new equipment was in- 
stalled in considerable quantity. 

The sonar course proved highly effective, not 
only because the men could now use their ships 
to better advantage on war patrol, but the ad- 
ditional training enabled them to repair equip- 
ment casualties at sea. 

Field engineers also gave underway instruc- 
tion to submarine crews. At Pacific submarine 
bases, the engineers would go out on every sub- 
marine for one or two days instructing crews 
on the operation of electronic equipment. 

They even organized a storekeeper training 
course, to instruct the men on the classification 
and recognition of parts and equipment. At 
one time, repair and reconditioning of ships at 
the Brooklyn Navy Yard was being seriously 
impeded by the storekeeper’s lack of knowledge 
as to what certain gear looked like. If a radio 
material officer ordered an OAX, the store- 
keeper might waste several precious hours try- 
ing to locate it. So the group devised a system 
which helped the storekeepers to locate and 
recognize thousands of parts and pieces of 
equipment. 

The assistance given to staff commands was 
varied and extensive. Operating through the 


293 


THE FUNCTIONS OF FIELD ENGINEERS 


Bureau of Ships, at Navy yards and stations 
or with the forces afloat, field engineers: (1) 
modified an AP teacher for improving training 
facilities at the WCSS; (2) made circuit modi- 
fications and additions and changed RCA sound 
gear so it could be used with a HUSL BDI on 


installation of equipment, planned the curric- 
ulum, trained instructors; (6) planned and di- 
rected an expendable radio sono buoy [ERSB] 
school for air force personnel at ASW head- 
quarters in Oahu, and at the same time aided in 
solving problems of launching certain devices, 



Figure 5. Shore sonar laboratory at Navy Training School, Navy Pier, Chicago. 


ASW training ships; (3) redesigned the ar- 
rangement of sonar equipment in DE sonar 
huts, making the equipment more accessible 
and easier to maintain and operate; (4) intro- 
duced equipment and techniques of checking 
ship’s sonar equipment on arrival or departure ; 
(5) at the Chicago Navy Pier and the Treasure 
Island Training Schools, assisted with plan- 
ning the layout of equipment, procurement and 


designed a floating triplane radar target, and 
established a communications system for air- 
craft and ground station coordination; (7) su- 
pervised training and the development of 
attack techniques at the Submarine Chaser 
Training Center, Miami; (8) assisted in im- 
proving the use of sound equipment, repaired 
equipment, and trained personnel on destroyer 
escort shakedown cruises. 



294 


FIELD ENGINEERING 


Detection of Fundamental 
Difficulties 

An important part of the field engineer’s 
duties was to locate and diagnose equipment 
difficulties of recurrent character, making 
changes or corrections in the field, then sug- 
gesting design changes to the manufacturer 
through BuShips to correct such difficulties. 
This work required the closest cooperation of 
field engineers, manufacturers, laboratories, 
and naval officials. 

Field engineers “put out thousands of fires,” 
soldered many connections and made other 
emergency adjustments, but their fundamental 
job was to improve equipment. If a tube burned 
out they would fix it, but they were more con- 
cerned with determining from circuit design 
why the tube burned out. They went to the 
crux of difficulties to determine how the manu- 
facturer could alter or improve the design or 
production of equipment. 

The group’s modification of the bearing devi- 
ation indicator [BDI] is a good example of 
detecting difficulties. The BDI was developed 
after echo-ranging gear, and the first units 
were ineffective because the power transformer 
produced a 60-c hum. A field engineer discov- 
ered that the hum could be reduced by relocat- 
ing certain components in the equipment. His 
modifications were sent to BuShips and later 
were published in BuShips’ official radio in- 
stallation bulletin [RIB]. 

To detect fundamental equipment difficulties, 
a variety of experience and specialization was 
often necessary. For instance, one field engineer 
who was an experienced mechanical engineer 
had specialized in ASW ordnance. He was as- 
signed to a destroyer escort to determine why 
a hedgehog (Mark 10 projector) was difficult 
to train under sea conditions when fully loaded. 
Discovering that faulty lubrication of the trun- 
nion bearings under full load was causing the 
increase in friction, he suggested minor modi- 
fications in the lubricating points. His recom- 
mendations were accepted by the Bureau of 
Ordnance and distributed to the Fleets as 
ordnance alterations. 

Familiarity with all ASW devices was also 
necessary. In some cases, separate ASW de- 


vices, designed to operate integrally with other 
shipboard equipment did not always work as 
expected. For instance, one model of echo- 
ranging gear when connected would not pro- 
duce a trace on the recording paper of the 
range recorder to permit adjustment (no trace 
to zero zero) . The range recorder was used for 
dropping depth charges and when not in proper 
adjustment would have range errors of 20 yd 
or more. A trace was needed to determine the 
range accurately. Field engineers detected the 
inadequacies, put the equipment in proper op- 
eration, and sent suggestions for modification 
of the echo-ranging gear to the manufacturer 
through BuShips. Later the design section and 
manufacturer found a way to make the neces- 
sary changes in design. 

Wherever the field engineer went, he brought 
his wide experience to bear on problems in a 
highly complex war organization. A field engi- 
neer was able to increase the effectiveness of 
a harbor defense system because he could apply 
his knowledge of shipboard echo-ranging gear 
to a land defense system. The projector train- 
ing system of a harbor defense equipment 
needed simple repairs. The field engineer as- 
signed to clear up the trouble devised a differ- 
ent type of training control which he made from 
spare radar parts. His improvements were 
highly satisfactory and provided more accurate, 
trouble-free operation. While making the re- 
pairs, he made additional improvements in 
order to increase the effectiveness of the de- 
fense system. At that time the Navy’s harbor 
defense engineers had not had the opportunity 
to study shipboard sound equipment. The field 
engineer was able to improve the defense sys- 
tem because he could apply his experience with 
echo-ranging gear to equipment used in a dif- 
ferent field. 


15.4.3 Introduction of New Equipment 

As has already been seen, the field engineers 
introduced many new pieces of sound gear to 
the Fleets. The attack plotter and the bearing 
deviation indicator have been mentioned. Other 
gear introduced included: (1) applique com- 
ponents for maintenance of true bearing 


THE FUNCTIONS OF FIELD ENGINEERS 


[MTB] ; (2) console-type echo-ranging” gear; 
(3) JP and JT submarine sonic listening sys- 
tems; (4) WFA submarine sonar; (5) depth 
charge direction indication [DCDI] ; (6) the 
submarine noise level monitoring system 
[NLM] ; (7) the torpedo detection modification 
of WCA-2 sonar equipment [TDM]. 

In the field of ordnance, field engineers as- 
sisted in introducing the forward-firing hedge- 



Figure 6. Installing noise level monitor unit in 
forward torpedo room of submarine. 


hogs and mousetraps. Also, numerous training 
aids were introduced. 

In dealing with the early major problem of 
adapting and improving the existing under- 
water sound equipment, rather than introduc- 
ing complete new sound systems, field engineers 
converted or adapted a total of 85 types of 
equipment. In most cases the job was done with 
little or no interference with operations. 

The adaptation of the attack plotter to the 
attack teacher equipment (used in all sonar 
training schools) is a good example of the ap- 
plication of a new development to an existing 
complete system. 

The AP was designed to produce on a fluo- 
rescent screen the geographical plot of an entire 
ASW operation, showing the course of the sub- 
merged target, own-ship’s course, and other 


features, such as the predictor line. This opera- 
tion requires inputs from echo-ranging equip- 
ment, the gyro-compass and the ship’s pitome- 
ter log. 

The attack teacher is a shore-based synthetic 
device used for training personnel. To adapt 
the attack plotter to it was a difficult problem. 

When the AP was being designed and tested 
at sea, the Navy realized the need for training 
personnel to use it. The obvious way was to 
attach the AP to the attack teacher. Various 
ways of associating these two devices were dis- 
cussed, and a field engineer was assigned to 
study the problem and coordinate research. He 
had had previous development laboratory ex- 
perience and at one time had operated an early 
model of an AP while on sea duty. One of five 
possible methods of attaching the AP to the 
attack teacher was selected, and the engineer 
devised the attack aids adapter [AAA] as a 
practical method of integrating the plotter and 
attack teacher. 

Although the Navy training schools were 
eager to put this new device to work, it was 
impossible at first to manufacture them on a 
production basis. So five AAA’s were built 
and sent to the Fleet training schools. It was 
many months before AAA units were produced 
in any quantity, so the preproduction units of 
the AAA made it possible to instruct Navy 
personnel in the use of the AP much sooner 
than expected. Here again, the field engineer 
had helped bridge the gap between develop- 
ment and use of equipment. 

During World War II, as all existing devices 
were further modified, the teaching equipment 
in the schools fell far behind, and it, too, had 
to be modified. The field engineers helped to 
modify much of the teaching equipment. 

The story of two field engineers who were 
ordered to help install a bearing deviation indi- 
cator, maintenance of true bearing equipment, 
and an attack plotter on a ship at Pearl Harbor 
tells how engineers helped to introduce compli- 
cated devices to ASW crews. 

During the latter part of May 1944, several 
BDI, MTB, and AP units arrived in Pearl Har- 
bor to be installed in ASW craft. The units were 
checked and adjusted by the field engineers. 
The first ship selected for the installation of 


296 


FIELD ENGINEERING 


these three associated units was one with an 
excellent ASW record, so every effort was made 
to finish the job quickly and return the ship to 
active duty. 

The BDI units were of early manufacture 
and required field modification as there was no 
time to send them to the mainland for revision. 
Because the crew was unfamiliar with the 
equipment, arrangements had to be made so 
that these three units could be disconnected 
from the sonar gear in case of failure or dam- 
age. The field engineers furnished all the tech- 
nical information and devised a system of dis- 
connecting the equipment which the Navy yard 
produced. 

The two field engineers made the modifica- 
tions, checked and tuned the equipment, cor- 
rected the errors, and finished the job several 
hours before the ship’s scheduled sailing time. 
To do this they worked for a continuous 36-hour 
period. The ship’s subsequent report, a con- 
firmed sinking of a Japanese submarine, fur- 
nished ample reward to these men and their 
associates who helped to introduce this compli- 
cated equipment. 


15.4.4 Development of New Techniques 

Invariably, field engineering work led to the 
development of new systems or techniques of 
testing, appraising and operating equipment, 
and instructing personnel. Even ASW tactical 
operations were influenced. 

When field engineers were testing or inspect- 
ing shipboard equipment or training radio tech- 
nicians and sound men, they frequently found 
that the men did not use the sonar equipment 
efficiently because they did not know how to 
tune it properly. 

The group developed several methods of tun- 
ing echo-ranging projectors and receiver-am- 
plifiers to peak performance. They evolved em- 
pirical methods for general application of these 
methods to all ASW vessels. Cards as visual 
aids to enlisted men were developed which were 
suitable for easy dissemination and use in the 
sound rooms and these were printed in BuShips 
official publications. Two such cards were How 


to tune a receiver, and How to tune your QC 
driver. The cards were provided for shipboard 
coaching work and were convenient to use 
either lying-to or underway and helped to in- 
sure proper functioning of the equipment under 
any circumstances. 

The importance of such a contribution may 
be difficult to understand. But to the field engi- 
neers who saw so many inadequacies in the life- 
and-death business of fighting submarines and 
who observed these inadequacies in personnel 
as well as equipment, the widespread use of this 
simple method of assuring proper operation of 
vital equipment was extremely important. 

Another kind of assistance was the develop- 
ment of a system of measuring the sound con- 
ditions of submarines operating at various 
depths and speeds. The New London Laboratory 
had collected data at Pearl Harbor on the noise 
produced by submarines as a direct result of 
cavitation and had made studies to link the 
noise with the speed and depth. As a result, it 
was concluded that a definite relation could be 
established between speed and depth, and cavi- 
tation, which would vary only from boat to 
boat. 

Field engineers assigned to ComSubPac 
evolved field methods of making cavitation 
measurements. Procedures were developed for 
laying out operating schedules and preparing 
the gear for test runs. Considerable practice 
was required to distinguish cavitation from 
other noises. 

The data or “boat signature” was compiled 
for each submarine tested, and a chart was 
prepared showing the record of noise level be- 
fore and after propeller cavitation at various 
speeds and depths. These were curves of speed 
versus depth showing the boundary or thresh- 
old between cavitation and the absence of cavi- 
tation. These charts were then presented to the 
submarine skippers. 

Since propeller cavitation and other noise 
sources vary from time to time, particularly in 
war patrols when depth charges are dropped 
or when operating in shallow water, this 
method of measurement was extremely impor- 
tant. Skippers were able to operate under cer- 
tain conditions with at least a greater peace of 
mind when they had this information. Thus, 


SUMMARY 


297 


field engineers even helped to improve tactical 
operations. 


155 SUMMARY 

This unique cooperative effort of the men 
from the laboratories, factories, naval com- 
mands, and forces afloat efficiently accom- 
plished far more than anyone expected in the 
beginning. Because the engineers had been 
carefully selected and trained they were able 
to grease the wheels of ASW operations and 
weld the men and equipment into a single, 
highly efficient team. This could not have been 
done if all hands had not worked together. This 
cooperation, in summary, enabled the field engi- 
neers to: 

1. Speed up the use of many new devices that 
played an immeasurable part in winning the 
antisubmarine war in two oceans. 

2. Discover the facts on the inadequacies of 
old and new devices and report them to the men 
whose job was to correct and improve equip- 
ment. 

3. Expedite the development of new equip- 
ment and methods by reporting the improve- 
ments urgently needed. 

4. Train thousands of enlisted men and offi- 
cers in schools, laboratories, and in the sound 
rooms aboard ship. 

5. Supervise the installation of new and com- 
plicated equipment on ships, submarines and 
planes, and improve methods of operation and 
maintenance. 

6. Sell the men of the Fleets on the kind of 
work done by research organizations and field 
men and thus win the personnel’s confidence 
and understanding of the purpose and useful- 
ness of new devices. 

From the beginning, the field engineers 
knew that the group’s life would extend no 
longer than the period of emergency, and if the 
work were to be continued, someone else would 
have to be trained to carry on. Whenever they 
repaired a situation, before they turned to an- 
other job, they always trained Navy personnel 
to carry on. 

Early in the spring of 1944, the Navy pro- 
posed that an organization within the uni- 
formed Navy be developed as a permanent so- 


lution to the problem of making specialized 
engineering talent available. A subordinate 
command at the Naval Research Laboratory 
founded such an organization of officer engi- 
neers to serve as an installation, maintenance 
and operation group. 

Duiing the last year, the Field Engineering 
group trained 30 especially selected Navy sonar 
officers to form the nucleus of the Navy’s per- 
manent field engineering group. Today, the 
Sonar Section of the Electronic Field Service 
group, operating under the Naval Research Lab- 
oratory, closely corresponds with the wartime 
Field Engineering group. Thus, the work of 
field engineering is being continued in peace- 
time. 

There are good reasons for the continuation, 
since both in the Armed Services and in indus- 
try , there will always be the problem of coordi- 
nating the manufacture, installation, mainte- 
nance, and training in the effective use of newly 
developed instruments of warfare. 

If the nation ever faces another emergency, 
how could field engineering be improved? The 
men who worked so closely with the group at 
headquarters and in the field have had many 
suggestions. But it appears that most of the 
difficulties the group encountered in doing its 
job can be traced to its late start. When the 
organization was formed, the crisis was at its 
peak and there was no time for refinements. 
If there is another emergency, such a group un- 
doubtedly should be formed, trained, and put to 
work as quickly as possible. Since the Navy 
now has a permanent field engineering group 
within its ranks, it should be easier in the fu- 
ture to expand and train additional personnel 
more quickly. 

This raises the question of whether the 
Armed Services should again recruit civilian 
engineers for integration with the forces. This 
question cannot be answered here. But the suc- 
cess of the Field Engineering group should in- 
dicate that there will always be a place for 
civilian assistance. Civilians, operating under 
Navy jurisdiction, have a greater freedom of 
movement, freedom from routine duties, fresh 
contact with industry, and other advantages 
not always available to officers in the Services— 
advantages which are essential when speed and 


298 


FIELD ENGINEERING 


flexibility are at a premium. By using field 
engineers with wide industrial experience, the 
Navy’s research and development program is 
not limited to control experiments on the prov- 
ing grounds, but can be extended to the opera- 
tions of the Navy itself. The advantages of de- 
veloping and improving equipment under actual 


operating conditions have been described in 
previous sections of this chapter. 

When all hands, Service and civilian, are 
striving to win the same objective, and if each 
understands the functions and responsibilities 
of the other, then the result should be team 
work. And after all, it is team work that counts. 


APPENDIX 






Appendix A 


Refer to : 
QB/A16(A) 


NAVY DEPARTMENT 
Bureau of Ships 
Washington, D. C. 


April 10, 1941 


Chairman, National Defense Research Committee 
1530 P Street, N.W., 

Washington, D. C. 

Dear Sir : 


I have investigated the report of the Colpitts Committee and have noted 
particularly that it recommends the formation of a committee to investigate 
the problem of submarine detection. 

Inasmuch as your organization was formed for the specific purpose of 
handling such problems, it is requested that you undertake this study, and 
1 shall be pleased if you will let me know what arrangements I should make 
to cooperate with your organization. 


Very sincerely, 

( Signed ) S. M. Robinson 
Rear Admiral, U. S. N. 


Copy to : 

Rear Admiral H. G. Bowen, USN, 
Naval Research Laboratory, 
Bellevue, Anacostia, D. C. 

Dr. F. B. Jewett, 

195 Broadway, 

New York City 


Appendix B 
MEMORANDUM 

Plan for Handling the Problem of a Comprehensive 
Investigation of Submarine Detection 


Foreword 

This memorandum is in response to the re- 
quest contained in the letter of April 10, 1941, 
from Admiral S. M. Robinson, Chief of the 
Bureau of Ships (copy attached), to the Chair- 
man of the National Defense Research Com- 
mittee, asking that the latter body undertake 
the investigation of submarine detection in 
cooperation with the Bureau of Ships. It is in 
conformity with discussions which Dr. Bush 
and Dr. Jewett had had previously with the 
General Board of the Navy and with Admiral 
Robinson at their request. 

Pending final discussion with the Navy as to 
details of organization and allocation of re- 
sponsibility in cooperative undertaking, this 
memorandum is a recommendation of what 
NDRC thinks advisable. It is recognized that 
the plan suggested represents the outline of a 
basic organization which may be modified 
readily as new conditions arise. These new con- 
ditions may come either from developments on 
the scientific or on the military side. 

To facilitate consideration of what follows 
there is attached (Appendix B) a rough chart 
of what now seems best for NDRC organization 
in order to make maximum use of the facilities, 
both human and material, which should be ap- 
plied to the scientific research and initial de- 
velopment aspects of the problem. 

Objective 

The objective sought is: 

1. The most complete investigation possible 
of all the factors and phenomena involved in the 
accurate detection of submerged or partially 
submerged submarines and in anti-submarine 
devices. While the detection of submarines 
operating as surface craft permits the use of 
physical phenomena other than those adaptable 
to underwater detection (e.g., micro-waves), 
this memorandum is concerned primarily with 
the latter problem. NDRC is already largely en- 
gaged in developing the possibilities of these 
other phenomena in the location of surface craft 
and results in the general field will undoubtedly 
be applicable to the surfaced submarine. 


2. The development of equipment and meth- 
ods for use of promising means for detection 
to the point where their final embodiment in 
form satisfactory for naval operation can be 
undertaken by the regular Bureaus of the Navy. 

These investigations will involve study of the 
characteristics of ships as they relate to the 
optimum employment of promising methods 
and equipment. This aspect concerns the desir- 
able characteristics of ships employed for de- 
tection purposes and of submarines themselves, 
considered as targets. 

While primarily concerned with problems of 
offense, the investigations will necessarily in- 
volve considerations of defense. 

Facilities Required 

The facilities required are : 

1. A central control group in NDRC to pro- 
vide reasonable coordination of research work ; 
to arrange for special work with existing labo- 
ratories and Government facilities ; to maintain 
liaison with British development, etc. 

2. A suitable staff of the ablest scientists, 
engineers and designers available for work di- 
rectly on the problems involved. The scientists 
are mainly physicists and mathematicians ; the 
engineers mainly electrical and mechanical. 

3. A suitable number of assistants for labora- 
tory and test work. 

4. Access to university, industrial and gov- 
ernmental laboratories for specific research and 
development work, which can better be done in 
existing laboratories than in specially estab- 
lished laboratories. 

5. One or two special laboratories located at 
or near naval stations where marine facilities 
are available for test purposes and where sub- 
marines are normally based. Preferably these 
stations should be chosen with regard to easy 
access to existing university and industrial 
laboratories, and to sources of supply of appa- 
ratus and equipment. 

6. An oceanographic laboratory for the con- 
duct of basic transmission measurements in 
ocean water under different conditions ; for the 
collection of average transmission conditions in 


302 


APPENDIX B 


303 


areas of prospective naval operations as a guide 
to research and development work and sub- 
sequent use of detecting gear, and for the de- 
velopment of simple equipment and technique 
for measuring transmission characteristics 
quickly at any time and place. 

What NDRC Can Provide 

Both because of the authority vested in it by 
the Council of National Defense Order of Estab- 
lishment, and because of its nation-wide con- 
tacts with civilian science through the National 
Academy of Sciences, the National Research 
Council and the scientific societies, the NDRC 
can provide 1 and 2, part of 3 if necessary, 4 
and 6. 

Note: No. 6 is already provided for in the 
existing NDRC contract with the Woods Hole 
Oceanographic Institution. When this contract 
was entered into it was contemplated that ulti- 
mately one or more of the oceanographic insti- 
tutions on the Pacific Ocean would be brought 
into the cooperative program. 

NDRC is empowered to employ personnel, to 
make contracts with university and industrial 
laboratories, and to transfer funds to Govern- 
ment agencies which are in position to do re- 
search work on NDRC problems. 

It is in position to locate and secure the serv- 
ices of the most competent scientists and engi- 
neers needed for any work it undertakes. 

What the Navy Should Provide 

Because of the fact that the special labora- 
tories (5) should be located at or near naval 
stations ; that much of the testing equipment 
needed is of a marine or naval character ; that 
a considerable part of the assistant personnel 
required (3) can best be drawn from the en- 
listed or civilian ranks of the Navy, and because 
NDRC is not well equipped to organize and 
police such a specialized operating force, it 
appears that the Navy should provide a special- 
ized laboratory, much of the assistant personnel, 
and such of the equipment needed as is available 
to the Navy; further, that the responsibility for 
regular operation and policing should be under- 
taken by the Navy. 

Special Laboratories 

a. Character of Laboratories. 

A special laboratory or laboratories contem- 
plated in (5) are to be scientific research and 
development laboratories operated by NDRC 
either directly or through some local scientific 


institution acting as contractor for it, as seems 
simplest and best. 

ivttvd^i con ^ rac ^ or scheme is one which the 
NDRC employs generally and has found to be 
satisfactory. Under it NDRC retains full con- 
trol of operations but by making use of the con- 
tractor s established machinery for handling 
financial matters, etc., it is relieved of the 
necessity for setting up non-scientific agencies. 
Under this arrangement the contractor per- 
forms the necessary service functions at actual 
cost without profit. 

If these special laboratories are set up as con- 
templated, with the Navy furnishing part of the 
research and development personnel, the neces- 
saiy police and guard personnel, the responsi- 
bility for the non-scientific operation of the 
laboratories, the contractor will be concerned 
only with matters, including the payment of 
bills, for which NDRC is responsible. 

under its Act of Establishment the 
NDRC is authorized to cooperate with but not 
to supplant existing agencies of Government 
concerned with instruments and instrumen- 
talities of warfare, the research and develop- 
ment work at the special laboratories will be 
carried only to the point where regular produc- 
tion of promising devices can be undertaken by 
the Navy in accordance with its established 
procedure. The laboratories will, however, 
always be available for assistance, and it is 
assumed that the time and manner of transfer 
of development work will be by mutual agree- 
ment. 

It is assumed that wherever devices show 
definite promise of practical utility, the Bureau 
of Ships will be brought into intimate par- 
ticipation with the further work of initial de- 
velopment. In this way final standardization 
will be facilitated and expedited. 

b. Naval Participation in Laboratory Opera- 
tion. 

In order to insure that the research and de- 
velopment work be carried on with maximum 
efficiency, it is assumed that the Navy will detail 
an officer familiar with submarines and with 
the requirements of research and development 
work, together with whatever assistance by 
way of officer and enlisted personnel it may 
deem necessary, to act in cooperation with the 
scientific director of the laboratory. 

While this officer will be to a large extent a 
member of the scientific force, his primary func- 
tion, in addition to his purely operational duties, 


304 


APPENDIX 


will be to arrange for the provision of naval 
facilities needed in the conduct of the work; to 
provide for liaison with the local naval forces, 
etc. 

c. Number of Laboratories to be Established. 

While the research and development work 

contemplated to be done by NDRC might be 
carried on in a single large laboratory, it seems 
best to contemplate two laboratories working in 
reasonable cooperation under common direction. 

The reason for this arises both from the dis- 
tribution of potential scientific facilities and the 
distribution of naval interests on both the 
Atlantic and Pacific seaboards. 

A single laboratory would make it difficult to 
utilize fully and effectively all of the facilities 
which are available for utilization. 

On the scientific side there are large con- 
centrations of men and facilities on both coasts. 
Exact knowledge as to these and facility of 
usage will be most effective to a laboratory 
located in the region. In other words, the attack 
will be more powerful through two laboratories 
than through a single one which would have to 
use auxiliary facilities at a distance or move 
men too far from their permanent locations. 

This latter item is important because men can 
be used effectively at the special laboratories on 
a part-time basis if they are in position to em- 
ploy their existing facilities on portions of the 
main problem. 

d. Character of the Work at the Two Labo- 
ratories. 

While the general character of the research 
and development work at the Pacific and 
Atlantic Coast laboratories will be similar, it is 
thought that there should be some differentia- 
tion, and the attached chart, Appendix B, in- 
dicates this. 


Because of its closer proximity to Washington 
and to the large number of facilities available 
for completing the final stages of development, 
it would appear that the Atlantic coast labora- 
tory should have primary responsibility for the 
final stages of research and development on 
promising equipment which may arise from the 
work in either laboratory, and that if possible 
the director of the Atlantic coast laboratory 
should be a man who has had large industrial 
research experience, and particularly experi- 
ence in the development of equipment designed 
to meet naval requirements. 

Per contra, the Pacific coast laboratory might 
have primary responsibility for the carrying to 
completion of fundamental investigations which 
the work at either laboratory indicates to be 
promising and might best be directed by a man 
of wide experience in fundamental research who 
has specialized in a branch of physics most 
likely to be involved in the submarine detection 
problem. 

Tentative selection of two such men for the 
directorship is indicated on the chart, Appendix 
B. 

e. Location of the Laboratories. 

Consideration of all the factors, both scien- 
tific and naval, indicates that the laboratories 
might well be located at New London and San 
Diego. Both of these locations seem to fit in well 
with the distribution of scientific and naval 
facilities. Because of adverse winter weather 
conditions in the North Atlantic, which are 
likely to interfere with tests and experiments in 
the open ocean, it may be that a laboratory 
established at New London might have to be 
supplemented by a small testing unit at some 
place like Charleston, South Carolina, Navy 
Yard. 


APPENDIX B 


305 


Refer to : 
QB/A16(A) 


NAVY DEPARTMENT 
Bureau of Ships 
\Y as hington, D. C. 


April 10, 1941 


Chairman, National Defense Research Committee 
1530 P Street, N.W., 

Washington, D. C. 

Dear Sir : 


I have investigated the report of the Colpitts Committee and have noted 
particularly that it recommends the formation of a committee to investigate 
the problem of submarine detection. 

Inasmuch as your organization was formed for the specific purpose of 
handling such problems, it is requested that you undertake this study, and 
I shall be pleased if you will let me know what arrangements I should make 
to cooperate with your organization. 


Very sincerely, 

( Signed ) S. M. Robinson 
Rear Admiral, U. S. N. 


Copy to : 

Rear Admiral H. G. Bowen, USN, 
Naval Research Laboratory, 
Bellevue, Anacostia, D. C. 

Dr. F. B. Jewett, 

195 Broadway, 

New York City 


306 


APPENDIX 


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Appendix C 


April 18, 1941 


Hear Admiral S. M. Robinson 
Bureau of Ships 
Navy Department 
Washington, D. C. 

Dear Admiral Robinson : 


This is in reply to your letter of April tenth (your reference QB/A16 
/4^’ le q ue st>ng that _ the National Defense Research Committee under- 
take a study of anti-submarine devices and asking to be advised as to what 
arrangements you should make to cooperate. 

Enclosed herewith is a memorandum which outlines the general form of 
the set-up which we think best for a major attack on the problem. As the 
memorandum indicates, the proposed arrangement involves intimate co- 
operation between the Navy and NDRC and answers your question as to 
the form of that cooperation. 


This memorandum has been considered by the National Defense Research 
Committee and is approved by them. If you concur, we will proceed to 
organize the special committees or sections contemplated, and to put the 
plan in operation as promptly as possible. 


Very truly yours, 

( Signed ) V. Bush 
Chairman 


Copy to : 

Admiral Bowen 
Dr. Jewett 


Address 

Bureau of Ships, 
Navy Department 
and refer to No. 
QB/A16 (A) 


Appendix D 

NAVY DEPARTMENT 
Bureau of Ships 
Washington, D. C. 


18 April 1941 


Chairman, National Defense Research Committee, 

1530 P Street, N. W., 

Washington, D. C. 

Dear Sir : 

I have just received your letter of April 18th giving a suggested set-up 
for handling the problem of a comprehensive investigation of submarine 
detection. 

The plan seems to be satisfactory, and I shall be very pleased to get the 
necessary arrangements for carrying it out started in accordance with our 
conference this afternoon. 


Very sincerely, 
{Signed) S. M. Robinson 
Rear Admiral, U. S. N. 


Appendix E 


NATIONAL DEFENSE RESEARCH COMMITTEE 
of the Council of National Defense 
1530 P Street, N.W. 

Washington, D. C. 


April 21, 1941 

MEMBERS OF THE NATIONAL DEFENSE RESEARCH COMMITTEE. 
Gentlemen : 

Admiral Robinson, Chief of the Bureau of Ships, has approved the plan 
which we placed before him in regard to a comprehensive and cooperative 
attack on the problem of submarine detection. Dr. Jewett’s Division is 
hence proceeding actively to put the plan into effect. 

Very truly yours, 

( Signed ) V. Bush 
Chairman 


Appendix F 

Outline of Fundamental Research Work on Under-Water Acoustics 


March 18, 1941 
Revised April 1, 1941 

Mr. 0. E. Buckley: 

Our recent discussions on submarine detec- 
tion and signaling, acoustic mines, and other 
related military problems involving the use of 
sound waves in water, have brought attention 
again to the need of fundamental research on 
under-water acoustics. It seems to me that to 
provide a background for accomplishing specific 
military objectives a broad program of research 
work along these lines is badly needed. Stimu- 
lated by these recent conferences, I have at- 
tempted to put down briefly my conception of 
what such a program should comprise. 

The work has been classified under the fol- 
lowing headings : 

1. Measurement tools and techniques. 

2. Development of instruments for convert- 
ing electrical vibrations into hydroacoustic 
vibrations — hydroacoustic generators. 

3. Development of instruments for convert- 
ing hydroacoustic vibrations into electrical 
vibrations — hydroacoustic detectors. 

4. Development of hydroacoustic generators 
and detectors having highly directional prop- 
erties. 

5. Study of transmission characteristics of 
water. 

6. Study of the boundary conditions and 
methods of locating submerged objects. 

7. Theoretical and experimental search for 
materials having high absorption for under- 
water sounds. 

8. Study and development of hydroacoustic 
sources having very great intensities. 

9. Exploration of noise and transmission con- 
ditions around ships in motion. 

10. Exploration of noise and transmission 
conditions in oceans and harbors. 

1. Measurement Tools and Techniques 

A great deal of the work done in air acoustics 
can be applied here. Vacuum tubes, amplifiers 
and oscillators, cathode ray tubes, etc., can be 
immediately applied both in the audio range 
and the ultrasonic range of frequencies. The 
development of devices for creating and picking 
up sounds in water having frequencies from 
zero to 100 kilocycles, and possibly higher fre- 


quencies, is needed. For part of this range satis- 
factory instruments are already available; for 
the other part further developments are neces- 
sary. 

2. Hydroacoustic Generators 

As a background for experimental work on 
hydroacoustic generators, theoretical consider- 
ation of what constitutes the ideal should be 
undertaken. Criteria should be set up for deter- 
mining how near any model approaches this 
ideal. Formulae should be developed to show 
how the various material factors affect the 
efficiency of any proposed generator. Experi- 
mental work should proceed with crystals, 
magnetostriction devices, as well as with elec- 
tromagnetic devices. Also a search should be 
made for other properties of matter which 
seem more ideally suited for under-water work 
than those now being considered. Particular at- 
tention should be paid to instruments which 
would stand the pressures encountered at very 
great depths. 

3. Hydroacoustic Detectors 

The work on hydroacoustic detectors should 
proceed along the same lines as those outlined 
for generators. 

4. Development of Hydroacoustic Generators 
and Detectors Having Highly Directional Prop- 
erties 

Work similar to that underlying the develop- 
ment of directional microphones in air is indi- 
cated here. Also the theoretical and experi- 
mental work on development of arrays of 
detectors for obtaining sharp directional prop- 
erties is included under this heading. 

5. Study of Transmission Characteristics of 
Water 

Although the transmission characteristics of 
air have been studied for centuries, it has been 
only in the last decade that the frequency 
selectivity of the air was discovered and under- 
stood. It is difficult to confine the low frequencies 
in a sharp beam and, on the other hand, very 
high frequencies are absorbed so rapidly that 
they can be transmitted only a short distance. 
This limits the useful frequency region for long 


310 


APPENDIX F 


311 


distance transmission to a small range of fre- 
quencies between 500 and 1500 cycles. Careful 
measurements in water may reveal a similar 
best frequency region for long distance trans- 
mission. Also the effect upon transmission of 
different physical conditions of the water is not 
thoroughly known. This is a large field for re- 
search but it is very vital for an understanding 
of under-water acoustics. 

6. Study of the Boundary Conditions and Meth- 
ods of Locating Submerged Objects 

The boundary conditions of the water will 
play an important part in determining the 
transmission possibilities just as is the case 
with sounds in the air. A particularly important 
phase of this subject will be the determinations 
of the best methods of locating the direction and 
distance to submerged objects. Pulsing methods 
similar to those used with radio detection of dis- 
tant objects should be studied. Particular at- 
tention should be given to methods of creating 
very intense pulses for a short interval of time. 

7. Theoretical and Experimental Search for Ma- 
terials Having High Absorption for Under- 
Water Sounds 

Wherever there is a boundary to a body of 
water containing acoustic waves, reflections 
occur. It is important to find methods of reduc- 
ing these reflections to a minimum. The experi- 
ence with air waves will be helpful here. Tanks 
equivalent to reverberation chambers will prob- 
ably be useful. Also tanks having a minimum 
reflection from the walls, corresponding to a 
dead room will be one of the first things that 
is necessary for accurate measurements. Theo- 
retical studies along the lines of acoustic filters 
in air may reveal combinations of materials 
which will be useful. 

8. Study and Development of Hydroacoustic 
Sources Having Very Great Intensities 

A study, both theoretical and experimental, 


to determine the maximum amount of acoustic 
power that can be put into water should be 
made. Such intense sound sources may have 
great military importance. They might be used 
to explode acoustic mines, or even might have 
damaging effects upon ships. For example, the 
depth bomb now used against the submarine is 
only an intense acoustic source. Such intense 
sound sources could be used for producing mask- 
ing effects upon other sound waves which the 
enemy are trying to use. There will probably be 
many uses for such sources, but the plan here 
is to consider the development of such sources 
entirely apart from their practical application. 

9. Exploration of Noise and Transmission Con- 
ditions Around Ships in Motion 

The work here is evident from the title. No 
doubt work along this line has been done, but 
only in a fragmentary way. A comprehensive 
survey of such noises in all directions from the 
ship should be made, paying particular atten- 
tion to conditions in very deep water. 

10. Exploration of Noise and Transmission 
Conditions in Ocean and Harbors 

Work along this line should follow the outline 
given for 9. 

To make the progress on this study that its 
importance warrants, a special laboratory 
should be set up adequate for twenty to thirty 
scientific workers with an equal number of 
helpers. It should be set up close to a large body 
of water where there is sufficient space to allow 
for large tanks of water which could be brought 
under laboratory control. Also, it is evident that 
a ship should be fitted out to carry out the work 
of exploring the noise and transmission condi- 
tions outlined above. The crew for manning the 
ship should be, of course, in addition to the 
numbers given above for carrying on the scien- 
tific investigation. 


H. Fletcher 


Appendix G 


March 27, 1941 


Suggested Program on Measurement Means and Technique for Under- 
Water Work 

1. Design and construct under- water microphones sufficiently stable and 
uniform to serve as secondary standards. Calibrate in terms of one or 
several, selected as prototype standard. Be prepared to furnish one or two 
instruments to each experimental group working on problem in order to 
provide a common reference. 

2. Proceed with establishment of an absolute calibration system, includ- 
ing primary standard microphones for under-water measurement. 

3. Design and construct series of under-water secondary standards to 
cover range from 0 to 50 kc. 

4. Design and construct suitable under-water radiators having deter- 
minable and stable output for use in quantitative measurement work. 

5. Design and construct directional devices for measurement purposes. 

6. Select and design suitable auxiliary apparatus including such things 
as amplifiers, detectors, recorders, oscillators, filters, cable for connection 
to under-water experimental devices. 

7. Be prepared to act as advisors on above matters to various groups 
working on the problem. 



312 



Appendix II 

Preliminary Memorandum on Magnetic Detection of Submarines from Moving Ships or 
Airplanes 


I Induced magnetic moments of submarines. 
Magnetic measurements upon four submarines 
of the U. S. Navy indicate that the vertical com- 
ponent of their induced magnetization is of the 
order of 1 to 2.5 X 10 5 C.G.S. per ton of dis- 
placement. These measurements refer to unde- 
gaussed submarines. The effective magnetic 
moment at large distances from degaussed sub- 
marines is unknown, but it is estimated by 
those familiar with present degaussing pro- 
cedures that degaussing is 80-90% complete. 
Available measurements are summarized in the 
table below. Here the first three boats were 
measured in the magnetic latitude of New 
London. The Sailfish measurements refer to a 
vertical field of .53 gauss and a horizontal field 
of .19 gauss (i.e., the magnetic latitude of Nor- 
folk). In the table, the symbols M z , M H , and 
M' h denote respectively the vertical component 
of magnetic moment, the horizontal magnetic 
moment, and the permanent horizontal mag- 
netic moment. In the case of the Sailfish , the 
permanent moment represents the residual 
value after demagnetization. 


Table. Induced Magnetic Moments of Submarines. 


Name 

Tons Length 

M z 

Perma- 
Mh nent 

M'h 

M z 

per 

ton 

Date 

D-2 

G-4 

L-ll 

Sailfish 

337 135' 
470 158' 
550 168' 
1450 

3X107 

5X107 

108 

3.5X108 

4X107 6X107 

2X108 5X107* 

.9X105 

1.1X105 

1.8X105 

2.4X105 

1918 

1918 

1918 

1940 

•After demagnetizing. 


II Size of German Submarines. The Ger- 
man submarines are of four sizes: 250 tons, 
500 tons, 900 tons ; also ocean going submarines 
of approximately 1800 tons. We may therefore 
expect the magnetic moment M z to be approxi- 
mately 2.0X10 7 for the smallest size and 
4.0x10 s for the largest sizes, before degaussing. 
After degaussing, the corresponding magnetic 
moments will presumably be 2x10° and 4xl0 7 
C.G.S. Clearly, further data concerning the 
magnetic moments of submarines are needed, 
especially for the smaller sizes, and after de- 
gaussing. 


L. B. Slichter December 14, 1940 

III The balanced coil method of detection. 
The balanced fixed coil type of magnetic de- 
tector is believed to be the best magnetic method 
for detecting submarines from a moving boat 
or plane. This method was especially studied by 
Professor Ernest Merritt at the Naval Experi- 
mental Station in New London in 1918. Under 
modern conditions, however, the sensitivity 
which was then achieved can be multiplied by 
a large factor of the order of a thousand. In 
this method two equal coils are used; one 
mounted in the bow, the other in the stern of 
the chaser.* They are connected in opposition 
and are rigidly mounted with axes closely 
parallel. Thus, the coils are theoretically bal- 
anced against the effects of roll and pitch in a 
uniform magnetic field. When the chaser 
(plane) is underway, the coil pair responds to 
anomalies in the earth's magnetic field in ac- 
cordance with the formula : 

E = 10~ 8 NA v x Ax (Eq. 1) 

where E = voltage differential on coil terminals., 
in volts. 

A = effective area of a coil, cm 2 . 

N = no. of turns per coil. 

Z = the component of the magnetic field 
perpendicular to the plane of the 
coils, in gauss. 

u x = ship's velocity component, cm. /sec. 

Ax = separation of coils, in the direction 
of x. 

It is assumed that the distance to the source of 
the anomaly is large compared to Ax, as it 
normally will be near the limits of range of 
the equipment. 

IV Magnetic anomaly due to submarines. 
At points in a horizontal plane at height h 
above the submarine, the vertical component, Z, 
of the magnetic anomaly due to the submarine's 
vertical magnetic moment, M zf is expressed by 
the following formula : 



* For obtaining direction, three coils may be used. 


313 


314 


APPENDIX 


Here, x represents radial distance in the hori- 
zontal plane from a center directly over the 
submarine (i.e., from the intercept of the dipole 
axis and the horizontal plane), and r 2 = x 2 + 
h 2 . There will also be a contribution to H z due to 
the horizontal magnetization M I{ of the sub- 
marine, but this is generally smaller. Its con- 
tribution will be neglected. The second deriva- 
tive, 
d 2 Z . 
a£i’ 18 

d 2 Z _qMJ 35x 2 h 2 
dx 2 r 5 * \ r 4 

V Natural fundamental limitations upon 
sensitivity of detection. 

(1) Time- fluctuations in earth's field. The 
coils must be balanced against differences at the 
two coils in the time-fluctuations of the local 
earth’s field. Experiments on land and in Boston 
Harbor indicate that two identical coils sep- 
arated distances of the order of 500' to 900', 
with an NA (see Eq. 1) as large as 10 10 C.G.S. 
may be balanced to % 0 microvolt in locations 
remote from artificial sources of electromag- 
netic disturbance. Thus, the effects of normal 
fluctuations in the earth’s magnetic field may be 
balanced out with high precision in these mag- 
netic latitudes. It will later appear that such 
fluctuations do not appear to set natural limits 
to the sensitivity of detection with techniques 
now available. (In high magnetic latitudes, 
magnetic storms are more frequent and intense. 
It is not known what limitations, if any, these 
will impose.) 

(2) Fixed geographic anomalies. The applica- 
bility of the method and the sensitivity which it 
will be feasible to use will be influenced by the 
magnetic character of the sub-oceanic geology, 
and by the depth of water. In water of depth 
600' to 2000', geologic structures may be ex- 
pected to produce anomalies of order 10 -14 to 

d 2 Z 

10 -11 in — :* (The normal latitude variation of 

dx 2 

d 2 Z 

the earth’s field produces values for — of about 

1.5 XlO -18 .) Experience and knowledge of the 

geological conditions will aid in predicting the 
sensitivities feasible to use. In deep water, 
topographic effects, and disturbances due to 

sunken ships will have a much longer “wave 
length” than a nearby submarine, and may be 


distinguished by this fact. Actual tests seem 
necessary to determine the geographical scope 
of application of the method. It is probable 
that in some areas it will be severely restricted 
in sensitivity by the geologic background. In 
other areas it is expected that the geologic back- 
ground will be found to offer little interference. 

VI Instrumental defects. The following is 
a list of the types of instrumental defects to 
which the method is subject. Plans for com- 
pensating for these defects are listed in the sec- 
tion following. 

(1) Error in parallelism , and effect of roll and 
pitch. Let the error in parallelism (angle between 
planes of coils) be €, and let the carrier ship 
rotate with amplitude 0 O and period P ; i.e., 

2tt 

0 = 0 O sin -p t, where 0 is the angle between the 

horizontal and the coil planes, which are assumed 
nearly “horizontal” when at rest. In a field of 
vertical component Z and transverse component 
H (in gauss), the resulting induced e.m.f. in 
volts due to rotation is 

E = 10 -8 NA 0 O cos -p f £ Z ^ e cos 0 — Tj- j 

+ H (e sin 0 + € 2 * ) J (Eq. 4) 

If, e = 1 sec. of arc, = 3 XlO -4 radian, 

Z = .5, 

H = .2, 

NA = 4 XlO 10 , 

0 O = 1/2 radian (30°), 

P = 6.28 seconds, 

then, E = 3 X 10 -2 volts, which is very large and 
must be reduced by compensation. 

(2) Thermal expansion of coils. The spuri- 
ous e.m.f. due to differential thermal expansion 
in the two coils is 

Et = 10~ 8 N Zo^' (Eq. 5) 

ot 

With a coefficient of linear thermal expansion of 
2.3X10 -5 (aluminum), 

E = 10-* Z„NA (4.6 XlO- 5 ) || (Eq. 6) 

d T 

where — is the time rate of change of the differ- 
ot 

ential temperature. Thus, for Z 0 — .5 and 


4 ) (Eq. 3) 


APPENDIX H 


315 


NA — 4xl0 10 , ten microvolts correspond to 
dT 

= 1 Xl0~ 3 c/sec. 

Conclusion. Coils must be compensated against 
differential temperature changes. 

(3) Thermal contact e.m.f.s. We are in- 
formed that thermal e.m.f.s. offer difficulties 
when detection voltages are of order 10 7 or 
less. For detection voltages of order 10 G or 
greater it is believed fluctuations due to thermal 
e.m.f.s. may be reduced to a satisfactory level. 

(4) Disturbances due to the Ship. Three 
types of local disturbances arising from the ship 
itself need consideration. (1) Movement of 
large iron parts such as anchors or swinging 
davits, tiller, and rudder mechanisms must be 
suitably restricted, or the parts must be made 
of non-magnetic materials. (2) The change in 
magnetic permeability with temperature of iron 
parts near the receivers may be of significant 
magnitude. (3) The effects of change in induced 
magnetization of the ship, with changing course, 
need special study. 

In an airplane, or in a semi-non-magnetic 
ship, the problem of local disturbances is obvi- 
ously much simplified. 

The problem of local disturbances is obviously 
a complex one. In the work at New London it 
was found that a steel ship could be used as 
effectively as a wooden one, but this result has 
little if any bearing on the present scheme, since 
we are now contemplating sensitivities a thou- 
sand fold greater than were then feasible to 
use. In brief, it has been estimated that in a 
wooden chaser of 110' length, the influence of 
engine is small, even for extreme values of the 
instrumental sensitivity, provided its tempera- 
ture change is of order 2° C/sec. or less. Simi- 
larly, preliminary computations indicate that 
the temperature effects in local iron masses are 
small provided the temperature changes are 

less than .1°C per sec., and the ratio - 03 < 1/4 

r 3 / 

where w = wt. in lbs., and r = distance from 
coil in feet. Thus, at 3 ft. uncompensated masses 
should be less than 7 lbs. 

The effects of change of course of the ship are 
difficult to estimate. They may be reduced by 
locating the coils parallel and near to the “mag- 
netic axis of the ship, and by automatically 
degaussing for changes in orientation. The 
pitching of the ship, however, will undoubtedly 
introduce severe difficulties. The best way for 


making progress in the study of the method is to 
use semi-iron magnetic ships, or airplanes. 

VII Compensation of errors. Errors due 
to lack of parallelism were compensated by 
Merritt in 1918 by a system of three auxiliary 
coils with planes mutually perpendicular. This 
procedure may be further improved by the ap- 
proximate neutralization of the normal com- 
ponent of the earth’s field at each coil. This 
could be done by use of an auxiliary winding 
on each coil, carring a current proportional to 
the cosine of the angle between the axis of the 
coil and the vertical. The effect of that part of 
the horizontal component of the earth’s field 
transverse to the axis of roll could also be 
neutralized— but the mechanism would have to 
take into account the orientation of the axis of 
rotation with respect to the magnetic meridian, 
and the normal intensity of the earth’s hori- 
zontal component. If 99% or more of the total 
component of the earth’s field normal to the 
plane of the coils were successfully eliminated, 
the influence of roll and pitch and also of tem- 
perature changes would be correspondingly re- 
duced. In the examples cited in section VI, there 
would remain a residual voltage of 3xl0~ 4 volts 
due to pitch, which must be further reduced by 
compensating coils to 1x10 5 in the design 
contemplated (see section IX). The differential 
temperature change permissible (see Equation 
6) would also fall within easily attainable limits, 
i.e., .1° Centigrade/sec., for a detection thres- 
hold of 10~ 5 volts. 

VIII Short period fluctuations. Spurious 
fluctuations due to vibration of parts or torsion 
in the ship may be eliminated by the introduc- 
tion of suitable filters, provided the disturbances 
are not of period comparable to that of the sig- 
nal to be observed. In the case of an airplane 
mount, the duration of the signal pulse will 
probably usually be between two and six sec- 
onds. In the case of a ship, about three times 
longer. (See sec. IX.) 

IX Detectability and range. The factor 
v ,Ax in Eq. 1 will be about the same size in 
either plane or ship installations. Thus, on a 
plane at 200 m.p.h., with a coil separation of 30 
ft., v x Ax is 10 7 C.G.S. ; on a boat at 20 knots, 
with coil separation 300 ft., vJAx is also 10 7 
C.G.S. The “wave length” of the response when 
passing directly over a submarine is about one 
and one-third times the height above the sub- 
marine. Thus, a boat at 20 knots (307 sec.) 
above a submarine submerged 300' would ex- 


316 


APPENDIX 


perience a response impulse of about 13 seconds 
duration. An airplane, at 500' above sea level, 
traveling at about 200 m.p.h. (300'/sec.) would 
experience an impulse of only 3% seconds dura- 
tion. At 100' submergence the time intervals 
would be 4*4 and 2% seconds, respectively. 

Because of the shorter time intervals involved 
with an airplane mount, and the need of mini- 
mizing weight, it seems essential to use a 
transformer on the coil-pair output. Some pre- 
liminary consideration has been given to the 
question of a proper transformer, and some 
preliminary model tests have been made. But 
the general question of the design of sensitive 
receiving equipment has been little considered. 

However, to illustrate in a crude way the 
order of magnitude of the ranges which might 
reasonably be expected, the following somewhat 
arbitrary example is set up. 

Assume (in Eq. 1) 

1 ) vj^x — 10 7 

2) NA = 8x10 s (Coil diameter — 1 meter, 
100,000 turns No. 36 enameled wire, wt. 78 lbs., 
resistance 415,000 ohms, inductance about 20,- 
000 henries) 

3) Transformer factor, /, = 50, 
so NAf = 4X10 10 

4) Assume that the threshold value of volt- 
age on the first tube of the amplifier is 10~ 5 
volts. Let the detection voltage, E, (Eq. 1) be 
ten times the threshold, or 10 -4 volts. 

Substituted in Eq. 1, the above values give 


5) After de-gaussing, let (a) M, = 2X10 6 for 
smallest submarines, and (b) M : = 4X10 7 for 
the largest. 

d 2 Z 

In Equation 3, the maximum — occurs at 

ax~ 

x = 0, and is there 

+ when § = 2.5X10-“ 

we find (a) r = 159 meters = 520' 
or (b) r = 285 meters = 935'. 


Thus under the assumptions made, the detec- 
tion range is of the order 500' to 1,000'. 

A measure of the area coverage in exploring 
an area for submarines is the product of the 
range attained by the speed of the searching 
vessel. Since air craft travel at ten fold the 
speed of destroyers, the ranges above are 
equivalent to 5,000' and 10,000' respectively, on 
surface craft, in terms of area explored per 
unit time. When one takes into account, in addi- 
tion, the relative first costs and costs of opera- 
tion of a ship and an airplane, the efficiency and 
economy of search by the magnetic method on 
planes may exceed that by standard methods on 
ships, despite the highly restricted range of the 
magnetic method. 


Balanced Coil Method of Detecting Submarines 
Summary 

A brief sketch of the problem of magnetic 
detection of submarines by the balanced coil 
method is here given. The range of the method 
is inherently short. Modern instrumental tech- 
niques should enable ranges on degaussed sub- 
marines of the order of 500' to 1,000' to be 
attained. The chief difficulties are not, appar- 
ently, fundamental and natural ones set by 
unavoidable background disturbances, but are 
those arising from local magnetic disturbances 
in the ship or plane. The sensitivity of detecting 
apparatus may be a limiting factor, if local 
disturbances are well eliminated by care in com- 
pensation. Apparently, little research on the 
method has been carried on in this country since 
1918, and it is believed that enough work 
should be done to establish the true limitations 
and possibilities of the method. Even the short 
ranges which it is estimated could be achieved 
with present apparatus may be important in 
searching for submarines by airplanes. Since the 
problem is primarily an instrumental problem, 
it seems reasonable to expect that distinct im- 
provements can be made through research. 


Appendix I 


September 19, 1940. 


Proposed Study of Oceanographic Aspects of the Sound Ranging Problem 


Introduction 

The research program outlined below is de- 
signed to supplement certain investigations on 
underwater sound transmission now in progress 
(or planned for) at the Naval Research Labora- 
tory, where work is for the most part directed 
towards improvement of the instrumental tech- 
nique, and towards the determination of the 
relationship between a given distribution of 
density in the surface layer and the effective 
range of various types of equipment. It is now 
proposed that this work be closely correlated 
with a thorough study of the oceanography of 
the surface layer with the ultimate aim of de- 
veloping a method for forecasting the sound 
transmitting characteristics of the waters in 
any part of the ocean, at any season and in any 
type of weather. 

The oceanographic part of this investigation 
will be centered at the Woods Hole Oceano- 
graphic Institution because some trained per- 
sonnel and equipment are immediately available 
there and because the strategical value of the ex- 
pected results makes it advisable to carefully 
select the investigators and to keep their finding 
secret. 

Objectives 

1. Immediate preparation of a manual, for 
use by both officers and enlisted personnel, sum- 
marizing a) the existing oceanographic knowl- 
edge relating to sound transmission, b) the 
physics of sound in sea water, and c) the results 
available in the sound file of the Naval Research 
Laboratory. 

2. Training of several pairs of observers and 
providing them with sufficient oceanographic 
background to collect on a large scale the neces- 
sary data from a) Naval ships, b) Coast Guard 
cutters, c) commercial steamers and d) avail- 
able oceanographic research vessels. 

3. From these observations areas will be 
mapped which can be considered a) reliable, b) 
unreliable, and c) safe only when seasonal and 
diurnal factors are fully taken into consider- 
ation. 

4. Study of the seasonal cycle and daily 


changes in structure of as many regions as is 
practical. 

5. Study of the influence of wind and evapo- 
ration so that in conjunction with daily weather 
maps a method can be devised to estimate the 
effective range in areas towards which the fleet 
is maneuvering. 

6. Development of an instrument for directly 
and rapidly measuring the change in velocity of 
sound with depth. 

Outline of the Proposed Investigation 

1. Field Work 

a. The “Atlantis” will be employed in this 
work on approximately a half time basis. She 
will make cruises to secure data on the seasonal 
and diurnal changes in the basic structure of 
the surface layer in the various primary water- 
masses of the western North Atlantic. She will 
also begin a detailed study of wind currents, 
both as they come into the sonic problem and as 
they have a navigational importance. These re- 
sults will as soon as possible be applied to the 
critical areas of the Pacific. 

b. In addition, the oceanographic observa- 
tions which can be made from naval vessels en- 
gaged in sound experiments (such as the 
“Sammes”) will be supervised by one of the 
men trained at the Woods Hole Oceanographic 
Institution. A copy of these observations will 
immediately be made available to the Navy 
Department to aid in the interpretation of the 
sound ranging data. 

c. As soon as a trained personnel is available 
and as soon as the observational technique has 
been sufficiently standardized, pairs of ob- 
servers will be sent off on Naval, Coast Guard, 
commercial and scientific vessels to explore the 
oceans from the standpoint of sound as thor- 
oughly as time permits. 

d. If the results are sufficiently promising, it 
is planned that rapid surveys of certain critical 
areas will be made for the purpose of con- 
structing detailed temperature charts of the 
superficial layers. It seems probable that some 
of the Coast Guard vessels could be used for 
such work. 


317 


318 


APPENDIX 


2. Instrumental Development 

At the outset of the investigation the basic 
instruments will be the bathythermograph and 
the pressure operated sea sampler. Both of 
these need further refinement. However, it is 
also clear that the development of an instru- 
ment capable of directly measuring the changes 
in sound velocity with depth would be most de- 
sirable. The principles of such a device have 
already been worked out and construction can 
start as soon as funds are available. Further 
instrumental developments will no doubt be 
suggested as the investigation proceeds and as 
a better knowledge is gained of the Navy’s re- 
quirements. 

If the preliminary investigations are success- 
ful, it is expected that before long 8 tech- 
nicians will be needed for the field work and 
4-6 clerical assistants for the routine laboratory 
analysis. Some of these people will be supplied 
by various cooperating agencies. 

Cooperation 

Besides the cooperation of the Naval Re- 
search Laboratory various agencies have al- 
ready agreed to contribute assistance: 

a. Submarine Signal Company 
Technical advice and design of instruments. 

b. Woods Hole Oceanographic Institution 
Salary of three investigators, laboratory 
facilities and the use of the “Atlantis” on a 
part time basis. 

c. Scripps Institution of Oceanography 
Laboratory facilities and possibly part of the 
salary of one or more qualified men. 

d. Oceanographic Laboratory, University of 
Washington 

Laboratory facilities and possibly part of the 
salary of one or more qualified men. 

In addition, it is expected that it can be 
arranged with the U.S. Coast Guard to assign 
to this work a considerable proportion of the 
oceanographic personnel of the International 
Ice Patrol Service. 

Budget 

It will require at least two years to carry 
through the proposed oceanographic investiga- 
tion and related instrumental development. The 
best estimate which can now be given as to the 
cost of this work, over and above that con- 
tributed by cooperating institutions, is $100,- 
000. It is proposed that this money be paid to 
the Woods Hole Oceanographic Institution on 


a quarterly basis in 8 installments, but the 
actual investigation will be continued until the 
funds are exhausted, unless the National De- 
fense Research Committee advises that it be 
discontinued. 

3. Laboratory Work 

a. Within the next few months a manual will 
be prepared for use at the naval sound schools. 
This will admittedly be a stop-gap, but the 
existing oceanographic knowledge and the 
technical reports on operation of sound equip- 
ment now on file at the Navy Department will 
be summarized. This hand-book will be written 
in simple language so that it can be used in 
the training of enlisted men for sound duty. 

b. The existing oceanographic data will also 
be analyzed more technically and as the work 
progresses reports will be submitted to the 
Navy Department for distribution to the in- 
terested agencies. 

c. In the same way, the new observations to 
be collected by the “Atlantis” and other co- 
operating vessels will likewise be analyzed and 
from time to time reported to the interested 
naval people for criticism. 

Personnel 

The scientists and technicians engaged in 
this program will be selected by the Director 
of the Woods Hole Oceanographic Institution. 
However, as the work proceeds he will consult 
with the proposed sub-committee on submarine 
detecting of the National Defense Research 
Committee. In short he will be responsible for 
the personnel which secures and analyzes the 
observations, but will look for guidance and 
criticism on the course of the investigation 
from such outside qualified scientists and naval 
authorities as may be designated. 

The trained investigators already arranged 
for can be listed as follows : 

Physical oceanographers : 

C. O’D. Iselin 
R. B. Montgomery 
M. C. Ewing 

Oceanographical and instrumental tech- 
nicians : 

A. C. Vine 
A. H. Woodcock 
J. L. Worzel 

In addition, it is expected that Dr. Fleming 
or Dr. Revelle of the Scripps Institution of 
Oceanography and Dr. Church of the Oceano- 
graphic Laboratory of the University of Wash- 


APPENDIX I 


319 


ington can be persuaded to join the investiga- 
tion. Additional technicians will be trained as 
needed. However, only the 4 or 5 senior men 
will be completely informed as to the practical 
objectives of the program. 


Breakdown of Expected Expenses Over a 
Period of Two Years 

1 . Field Work 

a. “Atlantis” The Woods Hole 
Oceanographic Institution will con- 
tinue to pay her normal operating cost, 
approximately $38,000 per year. How- 
ever, under the proposed program 
there will be an increase of roughly 


15%, due to additional time at sea ... $ 12,000 
b. “Anton Dohrn” This smaller 
vessel will be used for at least two 
months each summer 4,000 


c. Traveling The traveling ex- 
penses of senior investigators between 
Woods Hole, Washington and Cali- 
fornia, and the cost of sending the 
technicians to join cooperating vessels 
will not be inconsiderable 3,000 


2 . Instrumental Development and Winches 

2 Bathythermographs and 4 multiple 

sea samplers with auxiliary equipment 5,000 
Sound Velocity Meter 10,000 

3 Special high speed, portable 

winches 

3. Laboratory Rental , 

During the winter' months espe- 
cially, the Woods Hole Oceanographic 
Institution will be put to additional ex- 
pense for heat, light, power and minor 
laboratory supplies 

4. Salinity Determinations 
A very large number of water 

samples must be analyzed 

5. Personnel 


4,500 


3,000 


4,000 


Dr. Ewing $9,000 

Mr. Vine 5,000 

Mr. Woodcock 4,000 

Mr. Worzel 4,000 

Dr. Fleming, i/ 2 time 3,500 

Dr. Church, i/ 2 time 3,000 

4 additional field technicians 16,000 

2 laboratory assistants 7,000 

Stenographer 3,000 


54,500 


Total 


$100,000 



BIBLIOGRAPHY 


Numbers such as Div. 6-646.12-M11 indicate that the document listed has been microfilmed and that its 
title appears in the microfilm index printed in a separate volume. For access to the index volume and to 
the microfilm, consult the Army or Navy agency listed on the reverse of the half-title page. 


1. The Anti-Submarine Scatter Bomb (Final Report) , 17. 

OSRD 5494, NDRC 6.1-sr673-2346, Service Project 
NO-116, ARF, June 1945. Div. 6-646.12-M11 18. 

2. The Development of a Navigational Marker Buoy 

(Final Report), OSRD 5658, NDRC 6.1-srl224- 
2347, ARF, June 1945. Div. 6-646.33-M4 19. 

3. Supersonic Prism (Final Technical Report), OSRD 
389, NDRC C4-sr54-051, BTL, Dec. 20, 1941. 

Div. 6-635. 212-MI 

4. Magnetic Tape Compensator (Final Technical Re- 20. 
port), OSRD 688, NDRC C4-sr352-088, BTL, Apr. 

30, 1942. Div. 6-121.2-MI 

5. Magnetic Airborne Detector Apparatus for Differ - 21. 

ential Coil Method (Final Technical Report), 

OSRD 885, NDRC C4-sr40-084, BTL, June 20, 1942. 

Div. 6-425-MI 

6 . Magnetic Airborne Detector , Development of a 
Magnetic Orienting System (Final Technical Re- 
port), OSRD 1309, NDRC 6.1-sr367-535, BTL, Jan. 

4, 1943. Div. 6-425-M2 

7. Hydrophonic Calibration , Development of Tech- 
nique and Facilities , Reginald L. Jones, OSRD 
1489, NDRC 6.1-sr212-839, BTL, Apr. 15, 1943. 

Div. 6-552-M9 

8. Phase-Actuated Locator (Final Report), OSRD 
1897, NDRC 6.1-sr695-997, BTL, Aug. 30, 1943. 

Div. 6-622.1-M2 

9. Magnetic Airborne Detector , Investigation of Mag- 
netic Noise (Final Technical Report), OSRD 2084, 

NDRC 6.1-sr967-llll, BTL, Oct. 14, 1943. 

Div. 6-414-M3 

10. Magnetic Airborne Detector , Investigation of Mag- 
netic Noise (Supplemental Report), OSRD 3148, 

NDRC 6.1-sr967-1320, BTL. Div. 6-414-M6 

11. Torpedo, Mark 27 (Final Technical Report), 

NDRC 6.1-srl294-2338, BTL, Aug. 17, 1945. 

Div. 6-912.3-MI 

12. Final Technical Report under Contract OEMsr- 
316, NDRC 6.1-sr346-1333, BTL, Aug. 24, 1945. 

Div. 6-121.1-MI 

13. Letter to Dr. John T. Tate, Subject: Final Report 
for Contract OEMsr-1189, William H. Martin, 

NDRC 6.1-srll89-2373, BTL, Aug. 31, 1945. 

Div. 6-121.4-MI 

14. Final Technical Report of Contract OEMsr-1097, 

NDRC 6.1-srl097-1334, BTL, Sept. 28, 1945. 

Div. 6-910-M5 

15. Sea-Water Batteries (Final Report), OSRD 6420, 

NDRC 6.1-srl069-2128, BTL, Nov. 30, 1945. 

Div. 6-647-MI 

16. Final Technical Report for Contract OEMsr-783, 

NDRC 6.1-sr783-2384, BTL, Nov. 30, 1945. 

Div. 6-121. 3-MI 


692 Submarme Sondi^r, OSRD 6633, NDRC 6.1- 
sr692-2396, BTL, Feb. 28, 1946. Div. 6-633.3-MI 
Studies of the Jet Propulsion of Submerged Pro- 
jectiles, NDRC C4-srl24-495, Final Report 
CIT/RDC-1, CIT, June 1, 1942. Div. 6-111.1-MI 
Final Technical Report on OSRD Contract OEMsr- 
329, B. H. Rule and W. P. Huntley, OEMsr-329, 
Morris Dam Report 107, CIT, Mar. 25, 1944. 

Div. 6-111.2-MI 

Development of the High Speed Water Tunnel and 
Summary of Results, NDRC 6.1-sr207-2351, CIT, 
Aug. 31, 1945. Div. 6-711-M2 

Final Report on OSRD Contract OEMsr-20 for 
April 26, 1911 to August 31, 1913, Part I, New 
London Laboratory, Timothy E. Shea, Part II, 
Field Engineering Group, Timothy E. Shea and 
J. W. Kennard, Part III, Airborne Instruments 
Laboratory, D. G. C. Hare, Part IV, Program 
Analysis Group , William V. Houston, Part V, 
Underwater Sound Reference Laboratories, Robert 
b. Shankland, Part VI, Operational Research 
Group, Philip M. Morse and George E. Kimball, 
NDRC 6.1-sr20-2123, CUDWR. Div. 6-112-MI 

22 . Final Report Under Contract OEMsr-1128, Volume 
II, Manual for Antisubmarine Warfare Field 
Engineers , Timothy E. Shea, OSRD 6363, NDRC 
6.1-srll28-2128, Field Engineering Group, June 

30, 1945. Div. 6-112.11-MI 

23. Magnetic Airborne Detection Equipment (Final 

Report), OSRD 5486, NDRC 6.1-srll29-1773, AIL, 
July 15, 1945. Div. 6-401-M3 

24. Activities of the Underwater Sound Reference 
Laboratories for the period May 1, 1912 to Novem- 
ber 1, 1915 (Final Report), Robert S. Shankland, 
OSRD 6575, NDRC 6.1-srll30-2381, CUDWR, Oct. 

31, 1945. Div. 6-112.2-MI 

25. A Summary of the Work of the New London 

Laboratory on Equipment and Methods for Sub- 
marine and Subsurface Warfare, Timothy E. Shea 
and T. Keith Glennan, OSRD 5436, OEMsr-20 and 
OEMsr-1128, NDRC 6.1-srll28-2337, Final Report 
G22/R1426 covering the period from 1941 to 1945, 
NLL, June 30, 1945. Div. 6-112.1-MI 

26. Short Range Submarine Echoes, Kenneth H. King- 

don, OSRD 1084, NDRC C4-sr44-629, GE, Nov. 

21, 1942. Div. 6-122. 2-MI 

27. Magnetic Signal Device (Final Report), John H. 
Payne, Kenneth H. Kingdon, and others, OSRD 
917, NDRC C4-sr42-516, GE, Aug. 11, 1942. 

Div. 6-646. 4-MI 

28. [Development of Devices and Methods for Detect- 
ing Submarines by Magnetic Effects] Report of 
Work on Contract OEMsr-31 (Final Technical Re- 


321 


322 


BIBLIOGRAPHY 


port), Albert W. Hull, OSRD 1042, NDRC C4- 
sr34-536, GE, Oct. 24, 1942. Div. 6-422-MI 

29. Detection of Underwater Craft by Means of Short 

Pulses of Light (Final Report), C. Mannal and 
Elmer J. Wade, OSRD 1400, NDRC 6.1-sr43-870, 
GE. Div. 6-122.1-MI 

30. Antisubmarine Weapons and Devices (Final Re- 

port), OSRD 6430, NDRC 6.1-sr323-2387, GE, 
Nov. 15, 1945. Div. 6-122.3-MI 

31. Application of Sensitive Magnetic Devices to De- 
tection of Submarine from Aircraft (Final Re- 
port), OSRD 1870, NDRC 6.1-sr27-1107, Gulf Re- 
search and Development Company, July 1, 1942. 

Div. 6-421-M4 

32. Applied Acoustics in Subsurface Warfare, Final 
Report for Contract OEMsr-58 and Contract 
OEMsr-287 for the period 1941 to 1946, OSRD 
6658, NDRC 6.1-sr287-2097, HUSL, Jan. 31, 1946. 

Div. 6-113-MI 

33. Activities of the Massachusetts Institute of Tech- 
nology Underwater Sound Laboratory under Con- 
tract OEMsr-1046 (Final Technical Report), 
OSRD 5513, NDRC 6.1-srl046-2039, Research 
Project DIC-6187, MIT, Aug. 6, 1945. 

Div. 6-114-MI 

34. An Experimental Investigation of Torpedo Power 
Plants, Final Report under Contract OEMsr-1198, 
C. Richard Soderberg and Ascher H. Shapiro, 
OSRD 6348, NDRC 6.1-srll98-2385, Research 
Project DIC-6228, MIT, Aug. 31, 1945. 

Div. 6-830-M2 

35. Investigation of Torpedo Fuels, An Experimental 
Study of the Peroxide-Ethanol Cycle (Final Re- 
port), OSRD 6546, NDRC 6.1-srl289-2391, Service 
Project NO-236, MIT, Nov. 14, 1945. 

Div. 6-830. 2-M10 

36. Development of a Flotation Device (Final Report), 

K. A. Chittick, OSRD 44, OEMsr-33, Report 
D3/1248, RCA, Sept. 19, 1941. Div. 6-123-Ml 

37. Underwater Sound Direction and Range System, 
USDAR, OSRD 5315, NDRC 6.1-srl347-2331, 
Service Project NS-297, RCA, June 30, 1945. 

Div. 6-633. 23-M3 

38. Completion Report Covering Period June 1941 to 

April 1, 1946 (Final Technical Report), OEMsr-30, 
UCDWR, April 1946. Div. 6-116-MI 

39. Summary of Cavitation Tests on a Systematic 
Series of Rounded Torpedo Heads (Final Report), 
Hunter Rouse, John S. McNown and En-Yun Hsu, 
OSRD 5253, NDRC 6.1-srl353-2330, State Uni- 
versity of Iowa, May 31, 1945. Div. 6-810.23-M8 

40. Project Report and Instruction Book for Model 
XQHA Sonar Equipment (Serial 106), OSRD 
4946, OEMsr-1288 and NXsr-46933, Task No. 2, 
NDRC 6.1-1288-2117, BuShips and Sangamo Elec- 
tric Company, April 1945. Div. 6-632.221-M3 

41. Project [NO] -149, Mark 21 Torpedo, Final 
Technical Report under Contract OEMsr-1051, 
OSRD 5015, NDRC 6.1-srl051-2121, Westinghouse 


Electric and Manufacturing Company, Feb. 28, 
1945. Div. 6-911. 2-MI 

42. Mark 22 Torpedo, Final Report of Project [NO] 
-157, NDRC 6.1-srl053-2125, Westinghouse Elec- 
tric and Manufacturing Company, May 23, 1945. 

Div. 6-912. 2-MI 

43. Torpedoes for High-Speed Aircraft (Final Re- 

port), OEMsr-1342, NDRC 6.1-srl342-2334, Re- 
search Project 176, Newark College of Engineer- 
ing, 1945. Div. 6-115-Ml 

44. Final Technical Report under Contract OEMsr- 
1419, OSRD 6560, NDRC 6.1-srl419-2394, Leeds 
and Northrup Company, Nov. 30, 1945. 

Div. 6-125-MI 

45. Research and Development of Aerial-Type Tor- 

pedo (Final Report and Supplement), OSRD 6456, 
NDRC 6.1-srll05-2390, American Can Company, 
Dec. 31, 1945. Div. 6-124-MI 

46. Counter-Rotating Motor for Torpedo Drive (Final 

Technical Report on Contract OEMsr-1370), Ger- 
hard Mauric, OSRD 6659, NDRC 6.1-srl370-2397, 
Electrical Engineering and Manufacturing Cor- 
poration, Apr. 15, 1946. Div. 6-933-MI 

47. Sound Ranges under the Sea, Thomas H. Osgood, 
OSRD 660, NDRC C4-sr20-100, CUDWR, June 5, 

1942. Div. 6-500-MI 

48. Reverberation in Echo Ranging, Part 1, General 
Principles, Thomas H. Osgood, OSRD 807, NDRC 
C4-sr20-149, CUDWR, July 28, 1942. Div. 6-520-Ml 

49. The Magnetic Airborne Detector, Thomas H. Os- 

good and R. R. Palmer, OSRD 1124, NDRC 6.1- 
sr20-664, CUDWR, Dec. 19, 1942. Div. 6-423-M3 

50. Probability Studies for Patterns of Antisubmarine 

Contact Charges Launched from Surface Craft, 
H. R. Davidson, Conyers Herring, and Leonard I. 
Schiff, OSRD 1368, NDRC 6.1-sr20-834, CUDWR, 

Apr. 5, 1943. Div. 6-112-M3 

51. Reverberation in Echo Ranging, Part II, Reverber- 

ation Found in Practice, Thomas H. Osgood, OSRD 
1422, NDRC 6.1-sr20-840, Service Project NS-140, 
CUDWR, Apr. 14, 1943. Div. 6-520-M3 

52. A Theoretical Study of Factors Influencing the 
Effectiveness of Attacks Against Deep Submarines, 
Conyers Herring, OSRD 3885, NDRC 6.1-srll31- 
1153, Service Project NA-121, CUDWR, Dec. 13, 

1943. Div. 6-112.3-MI 

53. Probability Studies on the Effectiveness of Anti- 

submarine Attacks by Surface Craft, E. Ward 
Emery, OSRD 3916, NDRC 6.1-srll31-1426, 

CUDWR, June 2, 1944. Div. 6-112.3-M2 

54. A Theoretical Study of the Effectiveness of a 20- 

Knot Acoustic Torpedo and of Possible Modifica- 
tions Having Lower Speeds with or without an 
Automatic Speed-Changing Mechanism, Conyers 
Herring and E. Ward Emery, NDRC 6.1-srll31- 
1882, CUDWR, Nov. 22, 1944. Div. 6-912.4-MI 

55. A Torpedo Survey on Project N-121, NDRC 6.1- 

srll31-1892, Special Studies, CUDWR, Dec. 22, 
1945. Div. 6-900-M3 

56. Survey of Undemvater Sound, Report No. 1, In- 


BIBLIOGRAPHY 


323 


troduction , Vern 0. Knudsen, R. S. Alford, and 
J. W. Emling, 6.1-NDRC-729, Division 6, Feb. 26, 
1943. Div. 6-580-MI 

57. Survey of Underwater Sound, Report No. 2, 

Sounds from Submarines, Vern 0. Knudsen, R. S. 
Alford and J. W. Emling, OSRD 3247, 6.1-NDRC- 
1306, Dec. 31, 1943. Div. 6-580.1-M2 

58. Sonar Scanning Systems, Roy C. Hopgood, OSRD 
3220, 6.1-NDRC-1307, January 1944. 

Div. 6-600-MI 

59. Survey of Underwater Sound, Report No. 3, 

Ambient Noise, Vern 0. Knudsen, R. S. Alford and 
J. W. Emling, OSRD 4333, 6.1-NDRC-1848, Sept. 
26, 1944. Div. 6-580.33-M2 

60. Concluding Summary Report of the Selection and 

Training Committee Division Six, NDRC, Gaylord 
P. Harnwell, Dec. 15, 1944. Div. 6-300-MI 


61. Survey of Underwater Sound, Report No. U, Sounds 

from Surface Ships, M. T. Dow, J. W. Emling and 
Vern O. Knudsen, OSRD 5424, 6.1-NDRC-2124, 
June 15, 1945. Div. 6-580.2-M7 

62. Design of the Mark 25 Torpedo [Parts I and II], 

(Final Technical Report), OSRD 6672 and 6673, 
6.1-srll31-2393, Serv/ice Project NO-176, Dec. 31, 
1945. Div. 6-800-M6 

63. Bibliography and Brief Review of Published Ma- 
terial on the Physical Principles of Submarine 
Detection, Millard F. Manning, Conyers Herring, 
and David Keppell, OSRD 237, NDRC C4-sr20- 
018, CUDWR, September 1941. Div. 6-112-M2 

64. Method of Harbor Protection Against Non- 

Magnetic Submarine , L. B. Slichter and L. 
Batchelder, CUDWR. Div. 6-112-M4 


OSRD APPOINTEES 


DIVISION 6 

Division Personnel 


Until December 1942 work proceeded under direction of Section C-4 of Division C, NDRC. 
During this period Dr. F. B. Jewett was Chairman of Division C and Dr. John T. Tate Vice- 
Chairman, Division C, and Chairman Section C-4. In December 1942 Section C-4 became Division 
6, with Dr. Tate Chief of Division and Dr. Colpitts Chief of Section 6.1, the only section estab- 
lished. The Members of Section C-4 were reappointed as Members of Division 6 with exception of 
Drs. Carl D. Anderson, E. 0. Lawrence and Max Mason. The following persons served as Members 
of Division 6 for all or a portion of the period December 1942 to about December 1945, when their 
appointments were terminated. 


E. H. Colpitts 
W. D. Coolidge 
P. D. Foote 
G. P. Harnwell 

L. B. Slichter 


V. 0. Knudsen 
P. M. Morse 
G. B. Pegram 
T. E. Shea 


The following persons served as Technical Aides to Section C-4 and Division 6 for longer or 
shorter periods : 


Elmer Hutchisson, Head Technical Aide 
L. G. Straub, Head Technical Aide 
Richard H. Bolt, Chief Technical Aide 
L. F. Morehouse, Senior Technical Aide 
A. G. Anderson, Technical Aide 


A. W. Barrus, Technical Aide 
R. C. Hopgood, Technical Aide 
David Keppel, Technical Aide 
Dorothy M. Lasky, Technical Aide 
O. A. Wantuch, Technical Aide 


During period 1941-46 the Office Administrative Assistant was first Miss Fern Sullivan and 
later Mr. Joseph P. Lee. 


The following persons were appointed as Consultants to Division 6: 


R. D. Fay 
T. C. Fry 
T. K. Glennan 
D. G. C. Hare 
W. V. Houston 
F. V. Hunt 
V. 0. Knudsen 
D. P. Mitchell 


H. Nyquist 
T. C. Poulter 

R. S. Shankland 
H. W. Sverdrup 
M. S. Viteles 

E. G. Wever 

S. S. Wilks 
E. M. Wise 


324 


CONTRACT NUMBERS, CONTRACTORS, AND SUBJECT OF CONTRACTS 


Contract 

Number 


NDCrc-40 


OEMsr-20 


OEMsr-30 


OEMsr-34 


OEMsr-40 


OEMsr-42 


OEMsr-43 


OEMsr-44 


OEMsr-58 


OEMsr-27 


OEMsr-31 


Name and Address 
of Contractor 


Woods Hole Oceanographic Institution 
Woods Hole, Massachusetts 


The Trustees of Columbia University in the 
City of New York 
New York, New York 


The Regents of the University of California 
Berkeley, California 


General Electric Company 
Schenectady, New York 


Western Electric Company, Inc. 

120 Broadway, New York, N. Y. 


General Electric Company 
Schenectady, New York 


General Electric Company 
Schenectady, New York 


General Electric Company 
Schenectady, New York 


Harvard University 
Cambridge, Massachusetts 


Gulf Research and Development Company 
Pittsburgh, Pennsylvania 


Woods Hole Oceanographic Institution 
Woods Hole, Massachusetts 


Subject 


Studies and experimental investigations in 
connection with the structure of the super- 
ficial layer of the ocean and its effect on 
the transmission of sonic and supersonic 
vibrations. 

Studies and investigations in connection 
with the oceanographic factors influencing 
the transmission of sound in sea water. 

Studies and experimental investigations in 
connection with and for the development 
of equipment and methods pertaining to 
submarine warfare. 

Maintain and operate certain laboratories 
and conduct studies and experimental in- 
vestigations in connection with submarine 
and sub-surface warfare. 

Development of equipment and methods for 
detection of submarines by magnetic 
effects. 

Experimental studies and investigations of 
the development of equipment and meth- 
ods for detection of submarines by mag- 
netic effects. 

Studies and experimental investigations in 
connection with the development of mag- 
netic barnacles and non-magnetic stream- 
lined darts or stingers. 

Studies and experimental investigations in 
connection with the detection of sub- 
marines by light pulsing. 

Studies and experimental investigations in 
connection with short range submarine 
location utilizing short non-directional im- 
pulses. 

Studies and investigations in connection with 
the measurement of underwater noise 
from ships, and investigations of the 
transmission thereof through the medium. 

Studies and experimental investigations in 
connection with the development of equip- 
ment and methods applicable to the detec- 
tion of submarines by magnetic effects, 
including magnetic airborne detection. 

Studies and experimental investigations in 
connection with the structure of the 
superficial layer of the ocean and its 
effects on the transmission of sonic and 
supersonic vibrations. 


325 


CONTRACT NUMBERS, CONTRACTORS, AND SUBJECT OF CONTRACTS (Continued) 


Contract Name and Address 

Number of Contractor Subject 


OEMsr-33 

RCA Manufacturing Co., Inc. 

Camden, New Jersey 

Studies and experimental investigations in 
connection with the design and develop- 
ment of radio sonic buoys (capable of 
being dropped overboard from a ship). 

OEMsr-54 

Western Electric Company, Inc. 

120 Broadway, New York, New York 

Studies and experimental investigations in 
connection with the construction and test- 
ing of a supersonic prism as applied to 
methods of underwater ranging. 

OEMsr-212 

Western Electric Company, Inc. 

120 Broadway, New York, New York 

Studies and experimental investigations in 
connection with the development, construc- 
ton, and calibration of hydrophonic stand- 
ard receivers and projectors, and estab- 
lish and operate field stations necessary 
for the maintenance of a calibration sys- 
tem. 

OEMsr-315 

Goodyear Aircraft Corp. 

Akron, Ohio 

Studies and experimental investigations 
looking toward the development of stream- 
lined aerial housings for magnetic detec- 
tion equipment, including windtunnel and 
aircraft tests. 

OEMsr-124 

California Institute of Technology 

Pasadena, California 

Studies and experimental investigations in 
connection with jet propulsion of under- 
water detection devices and projectiles. 

OEMsr-352 

Western Electric Company, Inc. 

120 Broadway, New York, New York 

An exploratory development program to 
determine whether a magnetic tape com- 
pensator may be used to indicate the di- 
rection of incoming underwater sounds in 
submarine detection. 

OEMsr-287 

President and Fellows of Harvard College 
Cambridge, Massachusetts 

Studies and experimental investigations in 
connection with (i) the development of 
equipment and devices relating to sub- 
surface warfare. 

OEMsr-207 

California Institute of Technology 

Pasadena, California 

Construction and operation of a high-speed 
water tunnel, and use of such water 
tunnel in research and experimental in- 
vestigations involving underwater pro- 
jectiles and detection equipment. 

OEMsr-323 

General Electric Company 

Schenectady, New York 

Studies, experimental investigations, and 
development work in connection with sub- 
marine and subsurface warfare. 

OEMsr-329 

California Institute of Technology 

Pasadena, California 

Studies and experimental investigations in 
connection with the descent of underwater 
projectiles when falling freely and when 
initially propelled. 

OEMsr-346 

Western Electric Company, Inc. 

120 Broadway, New York, New York 

Studies and experimental investigations in 
connection with submarine and subsurface 
warfare. 


326 


CONTRACT NUMBERS, CONTRACTORS, AND SUBJECT OF CONTRACTS (Continued) 


Contract 

Number 


Name and Address 
of Contractor 


Subject 


OEMsr-367 


OEMsr-692 


OEMsr-695 


OEMsr-783 


OEMsr-785 

OEMsr-673 


OEMsr-967 

OEMsr-1069 


OEMsr-1051 


Western Electric Company, Inc. 

120 Broadway, New York, New York 

Western Electric Company, Inc. 

120 Broadway, New York, New York 


Western Electric Company, Inc. 

120 Broadway, New York, New York 


Western Electric Company, Inc. 

120 Broadway, New York, New York 


Western Electric Company, Inc. 

120 Broadway, New York, New York 

Armour Research Foundation 
Chicago, Illinois 


Western Electric Company, Inc. 

120 Broadway, New York, New York 

Western Electric Company, Inc. 

120 Broadway, New York, New York 


Westinghouse Electric Corp. 
Sharon, Pennsylvania 


Studies and experimental investigations in 
connection with the detection of sub- 
marines by rriagnetic methods. 

Conduct studies and experimental investiga- 
tions in connection with the development 
of listening and detecting systems suitable 
for surface craft and for submarines. 

Studies and experimental investigations in 
connection with methods of furnishing 
harbor protection by means of cables and 
associated equipment. 

Conduct studies and experimental investiga- 
tions in connection with, and develop 
calibration devices and methods in the 
field of hydrophonics, especially for cali- 
brating stations at Mt. Lakes, New Jersey, 
and Orlando, Florida, and more partic- 
ularly, (i) improve devices and testing 
equipment of types and range previously 
standardized for said stations, (ii) de- 
velop specific additional calibrating equip- 
ment and methods as requested; (iii) pro- 
vide an adequate number of models to 
equip said calibrating stations, and, (iv) 
perform such other related work as may 
be requested. 

Studies and experimental investigations in 
connection with Project 61. 

Conduct studies and experimental investiga- 
tions in connection with (i) the develop- 
ment and design of a satisfactory fuse for 
an armor-piercing “Scatter Bomb” and 
the development of one or more operating 
models as directed. ... (ii) such develop- 
ment work on the application of this fuse 
for use with the vertical bomb as appears 
to be necessary, and (iii) the design, de- 
velopment, and testing of special types of 
anti-submarine bombs and of their com- 
ponents and accessories. 

Studies and experimental investigations in 
connection with the phenomenon of MAD. 

Conduct studies and experimental investiga- 
tions in connection with the development 
of primary batteries having high power 
output per unit of weight and volume; 
such mechanical design as to permit, in 
addition to other incidental uses, their 
use in bombs or torpedoes launched from 
an airplane, from a ship’s deck, or from 
a submarine, etc. 

Studies and experimental investigations in 
connection with testing Mark 18 samples, 
and the design, development, construction, 
and testing of launching samples of an 
aerial torpedo, acoustically controlled and 
electrically propelled. 


327 


CONTRACT NUMBERS, CONTRACTORS, AND SUBJECT OF CONTRACTS (Continued) 


Contract Name and Address 

Number of Contractor Subject 


OEMsr-1053 


OEMsr-1097 


OEMsr-1046 


OEMsr-1189 


OEMsr-1105 


OEMsr-1128 


OEMsr-1129 


Westinghouse Electric Corp. 
Sharon, Pennsylvania 


Western Electric Company, Inc. 

120 Broadway, New York, New York 


Massachusetts Institute of Technology 
Cambridge, Massachusetts 


Western Electric Co., Inc. 

120 Broadway, New York, New York 


American Can Company 
230 Park Avenue, New York, New York 


The Trustees of Columbia University in the 
City of New York 
New York, New York 


The Trustees of Columbia University in the 
City of New York 
New York, New York 


Studies and experimental investigations in 
connection with testing Mark 19 samples 
and the design, development, construction 
and testing of two hand-made samples of 
an acoustically controlled, electrically 
propelled submarine torpedo. 

Conduct studies and experimental investiga- 
tions in connection with the development, 
design and construction of pre-production 
models of the acoustic and electronic ar- 
rangements required for Projects NO-149 
and NO-157, and such other development, 
design, and construction work in this con- 
nection that may be required. 

Studies and experimental investigations in 
connection with (1) underwater sound 
transmission and boundary impedance 
measurements; (2) ship sound surveys at 
high frequencies; (3) development of de- 
vices for the control of underwater 
sounds; and (4) development of intense 
underwater sound sources for special 
purposes. 

Provide the necessary personnel and facil- 
ities for manufacturing, stocking, and re- 
pairing hydrophonic instruments, equip- 
ment and apparatus. 

Conduct studies and experimental investiga- 
tions in connection with (i) the modifica- 
tion and improvement of torpedo design, 
with the general purpose of (a) enabling 
torpedoes to be dropped from aircraft 
without damage at higher speeds than is 
now possible and (b) improving the 
operating characteristics of torpedoes de- 
signed for high underwater speed; and 
(ii) the construction of experimental 
models of torpedoes or parts thereof for 
test purposes. 

Conduct studies and experimental investiga- 
tions in connection with and for the de- 
velopment of equipment and methods 
involved in submarine and subsurface 
warfare. 

Conduct studies and experimental investiga- 
tions in connection with the development 
and research work involving the applica- 
tion of magnetic methods to anti-sub- 
marine warfare including the development 
of airborne equipment and methods for 
training personnel in the use of such mag- 
netic methods, establishing the necessary 
laboratories and facilities for this pur- 
pose. 


328 


CONTRACT NUMBERS, CONTRACTORS, AND SUBJECT OF CONTRACTS (Continued) 


Contract 

Number 


Name and Address 
of Contractor 


Subject 


OEMsr-1130 

OEMsr-1131 

OEMsr-1198 

OEMsr-1294 

OEMsr-1224 

OEMsr-1288 

OEMsr-1289 

OEMsr-1347 

OEMsr-1342 

OEMsr-1370 

OEMsr-1419 


OEMsr-1353 


The Trustees of Columbia University in the 
City of New York 
New York, New York 

The Trustees of Columbia University in the 
City of New York 
New York, New York 


Massachusetts Institute of Technology 
Cambridge, Massachusetts 


Western Electric Co., Inc. 

120 Broadway, New York, New York 


Armour Research Foundation 
Chicago, Illinois 

Sangamo Electric Company 
Springfield, Illinois 


Massachusetts Institute of Technology 
Cambridge, Massachusetts 


Radio Corporation of America, RCA Victor 
Division 

Camden, New Jersey 

Newark College of Engineering 
Newark, New Jersey 


Electrical Engineering and Mfg. Corp. 
Los Angeles, California 

Leeds and Northrup Co. 

4901 Stenton Avenue, Philadelphia, Pa. 


The Iowa Institute of Hydraulic Research 
of the University of Iowa 
Iowa City, Iowa 


Conduct studies and experimental investiga- 
tions in connection with the testing and 
calibrating of acoustic devices. 

Conduct studies and investigations in con- 
nection with the evaluation of the 
applicability of data, methods, devices, 
and systems pertaining to submarine and 
subsurface warfare. 

Conduct studies and experimental investiga- 
tions in connection with (i) torpedo power 
plants and (ii) the general problem of 
power-plant design. 

Conduct studies and experimental investiga- 
tions in connection with production de- 
signs for the extension of Navy Project 
NO-94. 

Conduct studies and experimental investiga- 
tions in connection with the development 
of navigational marker buoy. 

Conduct studies and experimental investiga- 
tions in connection with (i) the engineer- 
ing development of a sonar scanning sys- 
tem for shipboard installation and (ii) 
the construction of three (3) preliminary 
models thereof, each model to be complete 
except for hoist mechanism. 

Conduct studies and experimental investiga- 
tions in connection with new and im- 
proved fuels for torpedoes, including 
survey of power supplies for jet-propelled 
missiles. 

Conduct studies and experimental investiga- 
tions in connection with the development 
of small object detectors. 

Conduct studies and experimental investiga- 
tions in connection with a development 
and test program for Navy Project NO- 
176. 

Conduct studies and experimental investiga- 
tions in connection with electric motor 
development. 

Conduct engineering studies and design work 
on a controlled mine, including some model 
shop work; engineering design and con- 
struction of a small number of the pre- 
production models. 

Conduct studies, experimental investiga- 
tions, observations, and tests of pressure 
distribution about underwater structures 
of varying form, together with photo- 
graphic records of the character of the 
flow, especially with reference to the 
onset and continuance of the phenomena 
of cavitation, all at varying speeds and 
under selected conditions of operation. 





329 


SERVICE PROJECT NUMBERS 


The projects listed below were transmitted to the Executive 
Secretary, NDRC, from the War or Navy Department through 
either the War Department Liaison Officer for NDRC or the Office 
of Research and Inventions (formerly the Coordinator of Re- 
search and Development), Navy Department. 


Service 

Project 

Number 


NCG-101 
AC-50 
AC-53 
AC-55 
AC-70 
AC-82 
N-118 
Ext. N-118 
N-121 
NA-99 
NA-107 

NA-120 
Ext. NA-120 

Ext. NA-120 
Ext. NA-120 
Ext. NA-120 
Ext. NA-120 
NA-121 
Ext. NA-121 
Ext. NA-121 

NA-123 

NA-143 

Ext. NA-120 

Ext. NA-143 


NA-174 
NO-94 
Ext. NO-94 
NO-96 


NO-lOO 
NO-116 
Ext. NO-116 
Ext. NO-116 
NO-121 
NO-125 
NO-141 
Ext. NO-141 

Ext. NO-141 


Subject 


Fire hose nozzles. 

Operations research. 

Development of a submersible magnetic tow target. 

Development of a directional radio-sonic buoy. 

Development of a hydrobomb. 

Special MAD project for Fifth Air Force. 

Assistance in the submarine training program. 

Development of a torpedo data computer trainer. 

Torpedo survey. 

Project Mike — plane carried magnetic sweeping equipment. 

Towed submarine listening gear for use with lighter-than-air 
craft. 

Magnetic detection from aircraft. 

Arrangements for measurement of time variations in the 
magnetic field of the earth. 

Construction of a magnetic attack trainer. 

Requirements for CM-2/ASQ-2B equipments (39). 

Four sets of bulk spares for the CM-2/ASQ-2B equipments. 

Request for six AN/ASQ-1A towed birds. 

Ordnance probability studies. 

Antisubmarine search procedure. 

Theoretical studies of the optimum patterns to be used in the 
so-called direct attack against submarines. 

Development of a recoverable bomb. 

A preliminary investigation of the possibilities and limita- 
tions of using MAD for BTO. 

MAD “Bird” for naval airship training and experimental 
command. 

Investigation of the use of MAD for low altitude detection 
of targets for the purpose of accurately placing shore 
bombardments in cases where the objectives are protected 
from observation by camouflage. 

Investigation of gas generating and high energy compounds. 

Mark — Mine. 

Devices for use by submarines against escort vessels. 

Fundamental investigation of (a) weapons for attacking sub- 
marines, (b) mine detection apparatus, (c) measurement 
and utilization of acoustic radiation from ships. 

Underwater photography. 

Scatter bomb for submarine attack by heavier-than-air craft. 

Scatter bombs (request for 200 complete clusters). 

Experimental test of AS scatter bomb and fuzes. 

Retro-rocket bombs for implementing MAD equipment. 

Oscilloscope course plotter — ASAP. 

Hydrodynamic characteristics of projectile forms. 

Study of British squid projectile type C and the U. S. 
Mark 11 depth charge. 

Request NDRC make a study of the pressure distribution 
around a model of the torpedo Mark 14 type at a simulated 
full scale speed of 45 knots at trim. 


SERVICE PROJECT NUMBERS (Continued) 


Service 

Project 

Number Subject 


Ext. NO-141 Study the hydrodynamic characteristics of the aircraft depth 
bomb, and Mark 53, Mod. 1, with nose fuze AN-M103 and 
hydrostatic tail fuze AN-Mark 230. 

NO-142 Attack predictors. 

Ext. NO-142 Attack director, Mark 3. 

Ext. NO-142 Request NDRC construct for BuOrd three sets of plan posi- 
tion from attack predictor scales (PPAP) for use with the 
attack plotter Mark 1 Mod. 2 to predict the course to steer 
the ship and the time to drop depth charges. 

Ext. NO-142 Construction of simple type of depth charge computer used 
in conjunction with a bearing recorder. 

NO-143 Electric detection (U.E.P.). 

NO-147 A/S projector Mark 10 — fire control equipment temporary 
installation. 

NO-149 Acoustic control for torpedoes. 

Ext. NO-149 Request for appointment of NDRC as consultant on develop- 
ment of special torpedo (NO-149). 

NO-157 Acoustically directed 21-inch torpedo for submarines. 

Ext. NO-157 Tests of model of German acoustic torpedo. 

Ext. NO-157 Consultant services for the adaptation of acoustic gear to 25 
preproduction models of the torpedo Mark 18. 

NO-163 Cooperation with the Navy in harbor surveys and surveys 
of ambient underwater noise conditions in various areas. 

NO-171 Proximity fuze for the Mark — mine. 

NO-175 Projected scatter charges for surface vessels. 

NO-176 Torpedoes for high speed aircraft. 

NO-177 Jet propelled torpedo for use from aircraft. 

NO-181 Echo-ranging control. 

NO-195 Depth charge pattern recorder. 

Ext. NO-195 Depth charge pattern recorder increased from 12 to a total 
of 30. 

NO-196 Anti-surface vessel ordnance. 

NO-200 Development of a sea water primary battery. 

Ext. NO-200 Request NDRC supply consulting services to BuOrd on 150- to 
300-kw batteries being supplied by Edison General Electric 
Appliance Company. 

Ext. NO-200 Development of special machinery for duplex type sea water 
battery. 

NO-204 Development of contact fuzes. 

NO-209 Stabilized roll indicator. 

NO-221 Acoustic spectograms of ship sounds. 

NO-222 Acoustic reflection fields of submarines. 

NO-226 Shipboard submarine attack teacher. 

NO-236 Investigation of torpedo fuels. 

NS-97 Selection and training program for sound operators. 

Ext. NS-97 Study on selection of sound operators attending Fleet Sound 
Schools. 

Ext. NS-97 NDRC sound operators selection and training project. 

Ext. NS-97 Production of QFL records and other training recordings 
displaying effects of FXR gear. 

Ext. NS-97 Assembly of an additional “B” unit for the echo recognition 
trainer. 

NS-102 Development of subaqueous microphones for sono-radio buoys 
and cable connected hydrophones. 

NS-106 Expendable sono-radio buoy. 

Ext. NS-106 Recordings of underwater explosions as heard over the ex- 
pendable sono-radio buoy. 

Ext. NS-106 Buoy operator trainer for the ERSB. 


SERVICE PROJECT NUMBERS (Continued) 


Service 


Project 


Number 

Subject 


NS-113 

Ext. NS-113 
NS-139 
NS-140 
Ext. NS-140 
NS-141 
NS-142 
Ext. NS-142 

Ext. NS-142 


Ext. NS-142 
Ext. NS-142 


Ext. NS-142 
NS-143 
NS-144 
Ext. NS-144 
Ext. NS-144 

NS-152 
Ext. NS-152 
NS-164 
Ext. NS-164 
Ext. NS-164 

Ext. NS-164 
Ext. NS-164 

NS-173 

NS-182 

NS-195 

NS-198 


NS-211 
NS-212 
NS-221 
NS-222 
NS-230 
NS-231 
NS-233 
NS-238 
NS-240 
Ext. NS-240 

NS-245 
Ext. NS-245 
NS-247 
Ext. NS-247 
NS-248 
NS-252 
NS-253 

NS-257 

NS-287 


Listening apparatus for small patrol craft and submarines 
toroidal magnetostriction hydrophone. 

50 Special 5-foot magnetostriction hydrophones. 

Testing and calibrating facilities. 

Acoustic properties of the sea bottom. 

Range as function of oceanographic factors. 

Acoustic properties of wakes. 

Basic improvement of echo-ranging gear. 

Request that a bearing deviation indication attachment be 
provided for attack teacher AirAsDevLant. 

7 models of a dynamic demonstrator (for training in the 
operation of the BDI), consisting in part of an artificial 
projector and Navy Type OAX monitor. 

Study of stabilization of sound projector. 

Development of a sturdy design of shipboard hoist equip- 
ment for Model OAX (modified) portable testing equip- 
ment. 

Procurement of 12 units FM sonar equipment. 

Acoustic marine speedometer. 

Echo repeater target. 

Echo repeater for use in submarine evasion tactics. 

Request construction of an echo repeater capable of being 
towed at pre-determined depths down to 800 ft. 

Shipboard attack teacher. 

Training device, SASAT B Model II. 

Submarine evasion device. 

Electronic noisemakers. 

Providing and loading disks for a certain Navy demolition 
outfit. 

Model NAC sound beacon. 

Development of a parachute buoyancy control for prosub- 
marine noisemakers which are heavier than water. 
Consulting services on SASAT Mark III equipments. 
Projector requirements and test limits. 

Consulting service on Model OAS and OAW practice targets. 
Consultant on contracts with Emerson Radio Phonograph 
Corporation and Freed Corporation for manufacture of 
expendible sono-radio buoys. 

Countermeasures to small depth charges. 

Noise reduction of submarines. 

Silent echo sounding equipment. 

Acoustic treatment of the conning tower. 

Reduction of interference on magnetic detection loops. 
Development of navigational marker buoy. 

Primary listening teacher. 

Depth charge direction indicator. 

Consulting service on shipboard antisubmarine attack trainer. 
Furnish consultant services to Librascope, Inc., on its de- 
velopment of a modification of the SASAT. 

Advanced listening teacher. 

Development and construction of group listening teacher. 
Triangular ranging. 

Assistance on triangulation-listening ranging system. 
Underwater voice communication system. 

Preparation of supplements to sonar instruction books. 
Time-motion study of operations in the submarine conning 
tower. 

Listening adjunct to submarine attack teacher. 

Periscope bearing indicator. 


332 


SERVICE PROJECT NUMBERS (Continued) 


Service 

Project 

Number 


Subject 


NS-293 
Ext. NS-293 

NS-294 

NS-297 

Ext. NS-297 

Ext. NS-297 
NS-301 

NS-308 

NS-316 


NS-321 

Ext. NS-321 
Ext. NS-321 
NS-324 
NS-325 


NS-326 
Ext. NS-326 
NS-329 

NS-330 

NS-337 


NS-339 

NS-342 

NS-355 

NR-100 


NAD beacon. 

CO xT S ^ ing service on Production of several types of model 
NAD sound beacons. 

Cavitation research. 

Detection of small objects by means of underwater acoustic 
devices. 

Request for 10 underwater sound small object locating de- 
vices (USDAR). 6 

Working models of the small object locator. 

Consulting services on underwater sound portable testing 
equipment. 

Sonar-surface and submarine bathythermograph instruction 
program. 

Consulting services to Bureau of Ships on Model NAC sound 
beacons at the Sound Equipment Corporation, Hollywood 
_ California, under Navy contract NXsr-60065. 

25 models of the extended range underwater sound portable 
testing equipment (7 to 70 kc monitor). 

Request for 7 expanded range monitors, 13 to 35 kc 
Procurement of 10 B-19H hydrophones. 

Sonar group operator trainer (2 units of). 

BI)I modification of the QFD advanced bearing teacher 
(operational test equipment Model 8) 25 units of for serv- 
ice test from Underwater Sound Laboratory, Harvard 
through a subcontractor. 

Artificial projector for operator training on shipboard 
monitor equipment Model OAX (10 units of). 

Consulting services on development of shipboard sonar 
monitoring equipment. 

Development of a device which provides automatic target 
positioning on dead reckoning tracers from an input of 
target range and bearing. 

Consulting services on production of radio transmitting 
equipments AN/CRT-4. 

W CA conversion equipments, consulting services on by 
“™ bla University Division of War Research to BuShips 

°"u ™? ntractS Nx sr-42164 (Task 9) and NXsr- 
65323 with RCA. 

Recognition recorder for use in training operators to recog- 
nize various ship and torpedo noises (4 models of). 

Attack teacher for QH type scanning sonar equipment. 
Consulting service on production of 24-volt seawater battery 
Operations research. 


OD-99 Determination of the dynamic characteristics of specified 
bomb and projectile shapes. 

0 °: 1 ^ Development of a high velocity open water channel. 
bC-64 Development and construction of expendable radio sonic 
buoy training device. 
































































♦ 
















































INDEX 


The subject indexes of all STR volumes are combined in a master index printed in a separate volume. For 
access to the index volume consult the Army and Navy Agency listed on the reverse of the half-title page. 


Acoustic calibrations, Mountain 
Lakes Station, 157 
Acoustic countermeasures in anti- 
submarine warfare, 112 
Acoustic torpedoes, 112, 209-221 
see also Torpedo research 
air-launched torpedoes, 215-218 
countermeasures, 112 
development history, 209-210 
echo-ranging control, 218-219 
electric torpedoes, 213-214 
future investigations, 219-221 
slow-speed torpedoes, 210-213 
Advanced bearing teacher, 252-254 
Airborne Instruments Laboratory, 
64-70 

laboratory facilities and equip- 
ment, 64-66 
personnel, 66 

research and development, 66-70 
Vacquier magnetic detector Mark 
1, 67 

Aircraft antisubmarine equipment, 
189-192 

magnetic airborne detector, 190- 
191 

radio sono buoys, 192-193, 235 
Aircraft in antisubmarine warfare 
convoy escort plans, 102 
countermeasures in the Bay of 
Biscay, 108-109 
detection equipment, 189-192 
disappearing contacts, 110-111 
history of use, 12, 16-18, 79 
“hunt” plans, 102-103 
gambit plans, 103 
materiel countermeasures, 109- 
111 

situation in Spring 1941, 19-20 
tactical countermeasures, 111- 
112 

World War II history, 79 
Aircraft torpedo research 
see Torpedo research 
Air-launched torpedoes, acoustical 
homing control, 215-218 
Allied shipping losses due to enemy 
submarines, 7-20 
convoy protection, 8 
logistical problem, 8 
World War I losses, 8-9 
World War II losses, 11-20, 75- 
79 

Allied shipping requirements for 
World War II, 8 


Allied submarine devices investiga- 
tion committee, 10-14, 21 
Anomaly, underwater sound trans- 
mission, 124-125 

Antisubmarine attack teachers, 
239, 262-263 

Antisubmarine detection equipment, 
9-10, 177-197 

aircraft antisubmarine equip- 
ment, 189-192 
harbor protection, 193-195 
NDRC program plans, 177-178 
small-object detectors, 195-197 
sonar scanning systems, 182-186 
sound gear monitors, 182 
statement of problem, 177 
surface antisubmarine warfare, 
178-189 

transducer development, 181-182 
Antisubmarine effectiveness, statis- 
tical analysis 

see Statistical analysis of anti- 
submarine effectiveness 
Antisubmarine operations research 
group (ASWORG) 
see Operations research in anti- 
submarine warfare, develop- 
ment 

Antisubmarine Organization, U. S. 
Navy, 79-80 

Antisubmarine training, practice 
targets 

see Practice targets for anti- 
submarine training 
Antisubmarine training devices 
see Sonar training 
Antisubmarine warfare, history 
see History of antisubmarine 
warfare 

Antisubmarine warfare, operations 
research 

see Operations research in anti- 
submarine warfare 
Antisubmarine Warfare Instruc- 
tor’s School, 249 

ASDevLant (Antisubmarine De- 
velopment Detachment) , 94- 
95 

ASDIC gear, 10, 13-14, 21 
ASDIC transducer, 149 
Attack aids adapter (AAA), 295 
Attack plotter, 290-292, 295 
Attack success evaluation methods 
for training, 261-262 


Aural detection of signals, 131 
Automatic gain control circuits for 
sonar receivers, 180-181 
reverberation-controlled gain, 
181 

time-varied gain, 180-181 

Balanced coil method of detecting 
submarines, 313, 316 
Bathythermograph (BT) 

antisubmarine training program, 
250-251 

data applications, 137 
prosubmarine training program, 
270-271 

Bearing deviation indicator (BDI), 
179-180, 249, 294 
Bearing teachers, 252-254 
British antisubmarine program 
magnetic detection of sub- 
marines, 67 

operations research, 82-84 
World War I, 8-11 
World War II, 11-20, 76 

Cape Henry system of harbor pro- 
tection, 195 

Cavitation in projectile research, 
172-174 

Civilian scientists, collaboration 
with Naval officers (per- 
sonal observations), 276-278 
Colpitts Committee, 26 
Combat Information Center trainer, 
273-275 
operation, 275 
purposes, 274 
training features, 274-275 
Conning teacher, primary, 254-256 
Convoys as protection from sub- 
marines 
history, 8 

World War I results, 8-9 
World War II, 11-17, 19, 78-79 
Countermeasures in antisubmarine 
operations, 108-112 
acoustic countermeasures, 112 
Bay of Biscay, countermeasures, 
108-109 

materiel countermeasures, 109- 
111 

radar, 108-112 

tactical measurements, 111-112 


335 


336 


INDEX 


Depth charge position indicators, 
205 

Depth-control mechanisms for tor- 
pedoes, 166 

Direction finders, high-frequency, 
15, 18 

Doppler effect in determining tar- 
get motion, 133-134 

Dynamic stability of torpedoes, 165 

Echo formation, underwater sound 
transmission, 129 

Echo ranges, maximum, 135-136 

Echo ranging, effects of ship self- 
noise, 130 

Echo recognition group trainer, 
(ERGT), 256-257 

Echo-ranging control project, tor- 
pedo, 218-219 

Echo-ranging equipment 
see also Sonar scanning systems 
ASDIC gear, 21 

Electric propulsion for torpedoes, 
161-162 

Electric torpedo, acoustical homing 
control, 213-214 
Mark 20; 214 
Mark 28; 214 
Mark 29; 214 
Mark 31; 214 

Electromechanical transducers and 
wave filters, 152 

Evasion aids for submarines, 205- 
208 

acoustic absorbing coating, 207- 
208 

depth charge position indicator, 
205 

noisemakers and decoys, 205-207 

Field engineering for subsurface 
warfare, 24, 279-298 
information branch, 287-289 
operations of engineers, 286-290 
responsibilities of engineer, 279- 
280 

summary, 297-298 

Field engineering for subsurface 
warfare, functions, 290-297 
attack plotter, 290-292 
detection of equipment difficul- 
ties, 294 

introduction of new equipment, 
294-296 

new technique development, 296 
staff assistance, 292-293 

Field engineering for subsurface 
warfare, organization, 280- 
286 


need for field engineering service, 
280-281 

operating principles, 283-284 
personnel procurement and train- 
ing, 284-286 
purpose of group, 282 
typical problems, 280-281 
Fleet sound school, 229-230, 247- 
248 

Fluctuation, underwater sound 
transmission, 128-129 
Fluid dynamics in projectile re- 
search, 167-174 
cavitation, 172-174 
development of laboratory, 168 
experimental facilities, 168-170 
laboratory program, 171-172 
projectile components, 172 
recommendations, 3 
FM sonar 

see Sonar scanning systems 
(QL) 

FM sonar (QLA), instruction, 268- 
269 

Future preparedness, subsurface 
warfare, 25 

German U-boat losses 
World War I, 9-10 
World War II, 12-14, 18, 75-76, 
78 

German U-boat sizes, 313 
German “wolf-pack,” 16-18, 75 
Group listening teacher, 267-268 
Group operator trainer, 257-258 

Harbor protection from enemy 
craft 

anchored radio sono buoy, 193- 
194 

cable-connected hydrophones, 
194-195 

Harvard Laboratory, 56-64 
bearing deviation indicator, 179- 
180 
costs, 64 
HUSL fleet, 61 

organizational development, 61- 
63 

personnel, 57-58 
physical plant, 58-60 
program, 56-57 

research and development, 63-64 
High-frequency direction finders, 
15, 18 

History of antisubmarine warfare 
convoys as protection from sub- 
marines, 8 

early submarine development, 7 
World War I, 8-11 


History of antisubmarine warfare, 
World War II, 11-20, 75-80 
NDRC program, 21-25 
period I — September 1939 to 
June 1940, 11-14 

period II— July 1940 to March 
1941, 14-19 

period III — April 1941 to Decem- 
ber 1941, 75-77 

period IV — January 1942 to 
September 1942, 77-79 
situation in Spring 1941, 19-20 
Huff-Duff, 15, 18 

Hydrodynamic behavior of tor- 
pedoes, 164-165 
Hydrographic charts, 138-139 
bottom sediment charts, 138 
sound ranging charts, 138 
submarine supplements, 139 
Hydrophones 

cable-connected for harbor pro- 
tection, 194-195 

development and calibration, 45 

IBM equipment in antisubmarine 
analysis, 104-106 
Italian submarine losses, 76 

Japanese submarine losses, 76 
JP listening equipment, instruc- 
tion, 268 

Laboratories 

Airborne Instruments Labora- 
tory, 64-70 

central laboratories, 29 
Harvard Underwater Sound Lab- 
oratory, 56-64 

New London Laboratory, 29, 36- 
47 

San Diego Laboratory, 47-56 
Underwater Sound Reference 
Laboratories, 32-35 

Magnetic airborne detector, 22, 
190-191, 235 

AN/ASQ-1 model, 190-191 
AN/ASQ-2, 191 
future development, 191-192 
Magnetic attack director, 250 
Magnetic detection of submarines, 
28 

Magnetic detection of submarines 
from moving ships or air- 
planes, 313-316 
balanced coil method, 313 
compensation of errors, 315 
detectability and range, 315 
induced magnetic moments of 
submarines, 313 


INDEX 


instrumental defects, 314 
limitations upon sensitivity of 
detection, 314 

magnetic anomaly due to sub- 
marines, 313 

Magnetic moments of submarines, 
induced, 313 

Magnetostriction transducer types, 
146-147 

asymmetrical laminated stacks, 
146 

laminated ring stacks, 147 
radially vibrating tubes, 146 
tube and plate transducers, 147 
Magnetostriction transducers, 144- 
148 

directivity theory, 147 
electromagnetic coupling, analy- 
sis, 145 

further development possibilities, 
148 

pilot plant facilities, 147 
properties of materials, 145-146 
types of transducers, 146-147 
vibrating system, analysis, 146 
Mark 2-1 stabilizer for torpedoes, 
163 

Mark 21 torpedo, 215-218 
Masking by noise, 131 
Masking by reverberation, 133-134 
Maximum echo ranges, determi- 
nants, 120 

Maximum echo ranges, prediction, 
135-137 

Maximum listening range, determi- 
nants, 120 

Mine detectors, 196-197 
Mountain Lakes Station, acoustic 
calibrations, 157 

NAC sound beacon, 206-207 
NAD sound beacon, 207, 270 
NAH sound beacon, 208 
Navy manuals, 138 
NDRC, background, 81-84 

British experience with opera- 
tions research, 82 
need for operation statistics, 81- 
82 

ordnance studies, antisubmarine, 
81 

NDRC, Division 6, operations re- 
search, 75, 80 

NDRC, Division 6, organization, 
26-71 

Airborne Instruments Labora- 
tory, 64-70 

central laboratories, 29 
early organization, 26-30 
expenditure for 1941-1942, 29 


Harvard Underwater Sound Lab- 
oratory, 56-64 

New London Laboratory, 36-47 
San Diego Laboratory, 47-56 
special studies group, 31-32 
Underwater Sound Reference 
Laboratories, 32-35 
NDRC, Division 6, program formu- 
lation, 21-25 
equipment, 21-22 
facilities, 24 
field engineering, 24 
fundamental research, 22-23 
operations research, 23 
personnel selection and training, 
23 

prosubmarine activities, 24 
torpedo program, 23-24 
NDRC publications, 137-139 
hydrographic charts, 138-139 
Navy manuals, 138 
NDRC sonar training assistance, 
236-242 

contractors’ training groups, 
241-242 

officer selection procedure, 240 
selection and training committee, 
236-241 

NDRC underwater sound program, 
121-122 

Navy observational program, 122 
San Diego contract, 121-122 
sonar analysis group, 122 
Woods Hole contract, 121 
New London Laboratory, 29, 36-47 
acoustic measurements and lis- 
tening tests at sea, 46 
data analysis and computations 
by Oceanographic Service, 
45-46 

electronic design and measure- 
ments, 45 

hydrophone development and 
calibration, 45 

laboratory facilities and equip- 
ment, 36-41 

Pearl Harbor Division, 46 
sound recording, 43-45 
staff organization, 41-46 
termination policies, 47 
Noise level monitor (NLM) in- 
struction, 270 
Noise reduction, submarine 
cavitation indicator, 204 
noise level monitor, 204 
OAY sound measuring equip- 
ment, 204 

Noise studies, sound transmission, 
129-131 


337 


ambient noise, 130-131 
masking by noise, 131 
self-noise (ships), 130 
types of noise, 130-131 
Noisemakers and decoys for sub- 
marines, 205-207 
NAC sound beacon, 206-207 
NAD sound beacon, 207, 270 
NAH sound beacon, 208 
pepper signal, 207 
XNAG sound beacon, 206 

Oceanographic studies for sub- 
marine detection methods, 
28-29 

Oceanography, research recom- 
mendations, 3 

Operations research in antisub- 
marine warfare, develop- 
ment, 85-96 

antisubmarine command, 90-91 
ASDevLant, 94-95 
assignment to bases, 88-89 
first research, 87 
incorporation with tenth fleet, 
92-94 

move to COMINCH, 87-88 
organization, 85-87 
publications, 97-98 
relations with Army Air Forces, 
89-90 

relations with British, 91-92 
sea search unit, 89-90 
Washington office, 89 

Operations research in antisub- 
marine warfare, Division 6; 
75, 80 

Operations research in antisub- 
marine warfare, research 
activities, 87, 97-116 
countermeasure in antisubmarine 
operation, 108-112 
data on flying, 106-107 
first research, 87 
importance of assessments of in- 
dividual attacks, 107 
reference library place in re- 
search, 114-115 

statistical analysis using punch 
cards, 104-106, 108 
submarine search problem, 98- 
104 

work at operational bases, 112- 
114 

Ordnance in antisubmarine war- 
fare, 10-11 

Peacetime research program, 
underwater sound, 139-143 
development program, 140 


338 


INDEX 


Navy research policy, 142 
pure research, 141-142 
research defined, 139-140 
supporting research, 140-141 
Pendulum depth-control mechanism 
for torpedoes, 166 
Pepper signal, 206 
Periscope attack trainers, 272-273 
Piezoelectric materials, 149-150 
ADP crystals (ammonium di- 
hydrogen phosphate), 150 
definition, 149 
quartz crystal, 149-150 
Rochelle salt crystals, 149-150 
Piezoelectric transducers, 148-155 
construction techniques, 152 
materials, piezoelectric, 148-150 
NDRC program, need for, 150 
need for transducers, 148 
summary of World War II 
achievement, 153-155 
UCDWR program, 150-152 
vibrating system, 150-152 
Plankton in volume reverberation 
studies, 132-133 

Practice targets for antisubmarine 
training, 260-261 
buoy type of echo repeater target, 
260 

raft and keel-mounted echo re- 
peaters, 260 
SR-2 type, 260-261 
SR-5 type, 261 

Primary conning teacher, 254-256 
Projectile research, fluid dynamics 
see Fluid dynamics in projectile 
research 

Projectile research facilities, 168- 
171 

controlled atmosphere launching 
tank, 170 

development of laboratory, 168 
free surface water tunnel, 171 
polarized light flume, 170 
water tunnel, high speed, 168- 
170 

Prosubmarine equipment, 198-208 
see also Sonar systems for pro- 
submarine warfare 
evasion aids, 205-208 
program review, 198-199 
submarine noise reduction, 203- 
204 

Prosubmarine sonar training pro- 
gram, 263-271 

bathythermograph program, 270- 
271 

FM sonar (QLA), 268-269 
group listening teacher, 267-268 
JP listening equipment, 268 


NAD beacons, 270 
noise level monitor, 270 
sound recognition group trainer, 
267 

torpedo detection modification, 
270 

training devices, 266-268 
Publications, NDRC 
hydrographic charts, 138-139 
Navy manuals, 138 

QH-QK sonar system 

see Sonar scanning systems 
(QH-QK) 

QL sonar systems (FM sonar) 
see Sonar scanning systems (QL) 
QLA, scanning sonar system, 22 

Radar as antisubmarine defense, 18 
Radar countermeasure problem in 
antisubmarine warfare, 108- 
112 

Radar operator’s course, 271 
Radio sono buoys, 22, 235, 250 
anchored, 193-194 

Reference library, place in anti- 
submarine research, 114-115 
routing, 115 
security, 114 

Refraction theory of underwater 
sound transmission, 125-127 
Research recommendations 

submarine countermeasures and 
counter-countermeasures, 3 
subsurface warfare weapons, 2-3 
underwater acoustics, 3, 120-121, 
310-311 

underwater acoustics, peacetime 
program, 139-143 

Reverberation studies, sound trans- 
mission, 131-134 

masking by reverberation, 133- 
134 

types of reverberation, 132-133 
Rocket characteristics tests, 172 

San Diego Laboratory, 29, 47-56 
engineering division, 51 
engineering services division, 54- 
56 

general organization, 47-51 
objectives, 50-51 
sonar data division, 51 
sonar devices division, 51-53 
training aids division, 53 
Schnorchel, 189 

Self-noise of ships, effects on echo- 
ranging, 130 


Shipboard antisubmarine attack 
teacher (SASAT), 239, 262- 
263 

Shipping losses, allied 

see Allied shipping losses due to 
enemy submarines 
Shipping requirements for World 
War II, allied, 8 
Shrimp noise, 130 
Signal detection, aural, 131 
Small object detectors, 195-197 
anchored vessel screening, 195- 
196 

mine detectors, 196-197 
Sonar, type B, 185-186 
Sonar analysis group, 31-32, 122 
Sonar art before World War II, 
226-231 

elementary sound operators class, 
229 

evaluation of training program, 
230-231 

fleet sound school, 229-230 
Sonar data division, San Diego 
Laboratory, 51 

Sonar devices division, San Diego 
Laboratory, 51-53 
Sonar equipment log, 249 
Sonar personnel selection, 276 
maintenance personnel, 244-245 
officers, 245-247 
operators, 242-244 
Sonar receivers, automatic gain 
control circuits 

see Automatic gain control cir- 
cuits for sonar receivers 
Sonar research, Division 6 
see NDRC, Division 6 
Sonar scanning systems (QH-QK), 
182-186 

commutated rotation (CR- 
sonar), 183-184 

depth scanning (type B sonar), 
185 

electronic rotation (ER sonar), 
184 

field tests, 184-185 
future development, type B 
sonar, 185-186 
QH system, 182-183 
Sonar scanning systems (QL), 
186-189, 268-269 
cobar, 187 
fampas, 187-188 
future development, 188-189 
pribar, 187 

QLA sonar, 188, 202-203, 268- 
270 

Sonar systems for prosubmarine 
warfare, 199-203 


INDEX 


339 


JP and JT listening equipment, 
199-200 

QLA sonar, 202-203 
692 sonar system, 201-202 
triangulation - listening- ranging, 
200 

WCA-2 modifications, 200-201 
XQKA (ER sonar) system, 203 
Sonar training assistance, NDRC 
see NDRC sonar training as- 
sistance 

Sonar training devices 

advanced bearing teacher, 252- 
254 

attack success evaluation meth- 
ods, 261-262 
CIC trainer, 273 

echo recognition group trainer, 
256-257 
films, 251-252 

group operator trainer, 257-258 
periscope attack trainer, 272 
practice targets, 260-261 
primary bearing teacher, 252 
primary conning teacher, 254-256 
recordings, 252 

shipboard antisubmarine attack 
teacher, 262-263 

tactical range recorder teacher, 
256 

underwater sound attack teacher, 
258-259 

Sonar training for prosubmarine 
warfare, 266-268 

Sonar training for World War II, 
231-236 

air participation, 235 
antisubmarine sonar schools, 
247-248 

new gear, 235-236 
radar operator’s course, 271-272 
strategic and tactical informa- 
tion, 256 

submarine interior communica- 
tions training program, 272 
subsidiary training projects, 248- 
251 

training handicaps, 231-234 
Sound beacons, 206-208, 270 
Sound control mechanisms for tor- 
pedoes, 166-168 
Sound gear monitors 
dynamic monitor, 182 
OAX monitor, 182 
OCP monitor, 182 
Sound measuring equipment 
(OAY), 204 

Sound recognition group trainer 
(SRGT), 267 


Sound schools, 229-230, 247-248 

Sound sources, underwater trans- 
mission, 123-124 

Sound transmission, noise studies 
see Noise studies, sound trans- 
mission 

Sound transmission, reverberation 
studies 

see Reverberation studies, sound 
transmission 

Static instability of torpedoes, 165 

Statistical analysis of antisub- 
marine effectiveness, 104-106 
card file used, 106 
design of code, 105-106 
punch cards, 105, 108 


Steering mechanisms for 

tor- 

pedoes, 

165-166 


proportional 

mechanisms, 

165- 

166 



two-position 

mechanisms, 

165- 

166 




Submarine detection 

from moving ships and airplanes 
by magnetic methods, 313- 
316 

oceanographic studies, 28-29 
problems involved, 9-10 
proposed requirements and or- 
ganization, 302-306 
Submarine interior communica- 
tions training program, 272 
Submarine noise reduction, 203- 
204 

cavitation indicator, 204 
noise level monitor, 204 
OAY sound measuring equip- 
ment, 204 

Submarine search problem, 98-104, 
178-189 

automatic gain control circuits, 
180-181 

barrier patrols, 101-102 
bearing deviation indicator 
(BDI) systems, 179-180 
convoy escort plans, 102 
detection methods, 178 
equipment arrangement, 178 
gambit plans, 103 
“hunt” plans, 102-103 
operational data, 99-100 
range and search rate, 98-99 
sighting probability curve, 100- 
101 

surface vessel search plans, 103- 
104 

Surface and bottom reflection, 
underwater sound transmis- 
sion, 127-128 


Surface vessels in submarine 
search, 103-104, 178-189 

Tactical range recorder teacher, 
256 

Target strength, underwater sound 
transmission, 129 
Torpedo, Mark 21; 215-218 
Torpedo, slow-speed, 210-213 
depth control, 211 
hydrophone problem, 211 
Mark 24; 212-213 
Mark 27; 213 

specifications, tentative, 211 
Torpedo detection modification 
(TDM), instruction, 270 
Torpedo echo-ranging control, 218- 
219 

Mark 32 mine (GE system), 218 
modified Mark 18 (HUSL sys- 
tem), 218 

Torpedo research, 23-24, 161-167 
air flight (aircraft torpedo), 

162- 163 

depth-control mechanisms, 166 
dynamic stability, 165 
propulsion (aircraft torpedo), 
161-162 

sound control mechanism, 166- 
168 

static instability, 165 
steering mechanisms, 165-166 
underwater run, 164-165 
water entry (aircraft torpedo). 

163- 164 

Torpedo stabilizer, Mark 2-1; 163 
Training aids, sonar 

advanced bearing teacher, 252- 
254 

attack aids adapter (AAA), 295 
attack teacher for shipboard, 
239, 262-263 

combat information center 
trainer, 273-275 

echo recognition group trainer 
(ERGT), 256-257 
films, 251-252 

group listening teacher, 267-268 
group operator trainer, 257-258 
practice targets, 260-261 
primary bearing teacher, 252 
primary conning teacher, 254-256 
recordings, 252 

sound recognition group trainer 
(SRGT), 267 

tactical range recorder teacher, 
256 

underwater sound attack teacher, 
258-259 


340 


INDEX 


Training aids division, San Diego 
Laboratory, 53 

Training for antisubmarine war- 
fare, 236-242, 247-251 
bathythermograph, 250-251 
bearing deviation indicator, 249 
expendable radio sono buoys, 250 
magnetic attack director, 250 
NDRC sonar training assistance, 
236-242 

sonar schools, 247-248 
subsidiary training projects, 248- 
251 


Transmission studies, underwater 
sound, 123-129 

attenuation coefficient, 124-125 
echo formation and target 
strength, 129 
fluctuation, 128-129 
refraction theory, 125-127 
sound sources, 123-124 
surface and bottom reflection, 
127-128 

Turbine propulsion for torpedoes, 
162 


Training for prosubmarine war- 
fare, 266-268 

Transducer, piezoelectric 
see Piezoelectric transducers 

Transducer program, 181-182 

Transducer program, UCDWR, 
150-152 

Transducer research and calibra- 
tion, 144-160 
facilities, 157-159 
future requirements, 159 
magnetostriction transducers, 
144-148 

peacetime applications, 159 
piezoelectric transducers, 148- 
155 

procedures for standardization, 
156-157 

program objectives, 155 
standards and calibration meas- 
urements, 155-160 
wartime achievements, 159 


UCDWR transducer program, ISO- 
152 

see also Transducer research and 
calibration 

equivalent circuits, 152 
vibrating system, 150-152 

Underwater sound, NDRC and 
Navy data, 122-139 
bathythermograph data applica- 
tions, 137 

equipment design, effects of basic 
research, 134-135 
maximum echo ranges prediction, 
135-137 

noise studies, 129-131 
publications, 137-139 
reverberation studies, 131-134 
transmission studies, 123-129 

Underwater sound, peacetime re- 
search program 

see Peacetime research program, 
underwater sound 

I 

41 


^CLASSIFIED 
By aUthorit y Secretary 0 f 


OCT 1 y 19 60 


Defense n,emo2A ugust 1960 

library of congress 

| 

LC REGULATIO N: BEFORE SERVICING ^ 
OR REPRODUCING ANV PART OF THIS 
DOCUMENT, ALL CLASSIFI CATION 
MARKINGS MUST BE CANCELLED: 


Underwater sound attack teacher, 
258-259 

Underwater Sound Reference Lab- 
oratories, 32-35 

Underwater sound studies 

see also Underwater sound, 
NDRC and Navy data 
NDRC procedures, 121-122 
peacetime research program, 139- 
143 

pioneering work, 119-120 
plan for fundamental research 
on underwater acoustics, 
310-311 

proposed studies of oceano- 
graphic factors, 317-319 
research needed, 3, 120-121 

Underwater sound transmission 
see Transmission studies, under- 
water sound 

Vacquier magnetic detector Mark 
1; 67-68 

Vacquier magnetometer, 67-69, 190 

Vixen (countermeasure to search 
receiver) , 110 

Volume reverberation studies, 132- 

133 

Wakes, acoustical properties, 129 

Water tunnel for projectile re- 
search, 168-170 

Woods Hole Oceanographic Insti- 
tution, underwater sound 
studies, 70, 121 

XNAG sound beacon, 206 

XQHA scanning sonar system, 22 


S me stE T 












DECLASSIFIED 
By authority Secretary of 

1 doj 

De£enSfe - ^gust I960 
LIBRARY ' OF CONGRESS 


0 * : bB !^?aS B of C 1 S 3 

r. A ^;si fc'l9i5S«: 






